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  • 1995-1999  (25)
  • 1970-1974  (102)
  • 1950-1954
  • 1999  (25)
  • 1972  (102)
  • 1860
  • Electron microscopy  (127)
Materialart
Erscheinungszeitraum
  • 1995-1999  (25)
  • 1970-1974  (102)
  • 1950-1954
Jahr
  • 1
    ISSN: 1432-1106
    Schlagwort(e): Key words Acetylcholine receptor ; Nicotinic ; Denervation supersensitivity ; Neuromuscular junction ; α-Bungarotoxin ; Immunocytochemistry ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Through the use of biotinylated-bungarotoxin and monoclonal antibodies, the nicotinic acetylcholine receptor (nAChR) was localized in the subneural apparatus of mammalian motor end plates of the flexor digitorum brevis muscle of the adult rat at the light and electron microscopic levels. Under normal conditions, nAChR was located in the primary post-synaptic membrane of the neuromuscular junction, and the depths of the junctional folds constituting the secondary post-synaptic membrane did not contain any nAChR. Up to 75 days after repeated transection of the related motor nerve (sciatic), there was no major alteration in the light-microscopic localization of junctional nAChR in the subneural apparatus, except for a moderate shrinkage and increased immunocytochemical reactivity of the subneural apparatus. At the electron microscopic level, however, immunocytochemical reactivity gradually occupied the entire extent of the secondary post-synaptic membrane, including the depths of the junctional folds, which exhibited extensive branching. In non-innervated portions of the muscle fibers, nAChR receptor appeared in a linear localization on the surfaces of denervated muscle fibers. This linear reaction was not continuous with the nAChR reaction of the motor end plates. It is concluded that denervation supersensitivity might not be due to spreading of junctional nAChR from the end-plate area, but rather to expression of nAChR in non-innervated portions of the muscle fiber and to the infraterminal (subsynaptic) spreading of nAChR into the depths of junctional folds.
    Materialart: Digitale Medien
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  • 2
    ISSN: 1437-773X
    Schlagwort(e): Key words Gastrointestinal stromal tumor ; Gastrointestinal autonomic nerve tumor ; Electron microscopy ; Immunohistochemistry ; Gastrointestinal tract
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Sixteen gastrointestinal stromal tumors (GISTs) were studied by immunohistochemical analysis and an ultrastructural procedure. The tumor locations were as follows: esophagus (2), stomach (7), small intestine (3), and large intestine (4). Four of the lesions were classified as malignant, 2 as borderline, and 10 as benign. On the basis of the immunohistochemical analysis, the tumors were classified as follows: 1 as myogenic type, 2 as Schwann cell type, 8 as Cajal cell type (including 2 gastrointestinal autonomic nerve tumors, GANTs), and 5 as mixed-cell type. In each subtype the phenotype was compared to the ultrastructural findings. Myogenic and Schwann cell type revealed ultrastructurally smooth muscle differentiation and schwannian tumor. All 8 tumors of the Cajal cell type revealed interdigitating cytoplasmic processes with occasional clusters of filopodia. Two tumors were subdivided as GANT. Five tumors of mixed-cell type were composed of a mixture of cells with variable myogenic features or variable neural differentiation. We confirmed in this study that immunohistochemical analysis reflected electron microscopic findings.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Medical electron microscopy 32 (1999), S. 209-212 
    ISSN: 1437-773X
    Schlagwort(e): Key words Keratin ; Bile canaliculi ; Ecto-ATPase ; Transgenic mice ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Keratin 8 (K8) and keratin 18 are the intermediate filament proteins that are expressed in hepatocytes. A K8-deficient FVB/N mouse is a unique animal model for assessing the contribution of keratin intermediate filaments (IFs) to the structural and functional integrity of hepatocytes. Hepatocytes from homozygous (−/−) K8-deficient mice manifest a reduced bile acid secretion and an increased fragility to mechanical stress and hepatotoxic drugs. Hepatocytes from heterozygous (+/−) mice are more susceptible to drug-induced injury. Immunofluorescent microscopy revealed that hepatocytes from (+/−) mice maintained K8 IFs and F-actin that are similar to those in wild-type (+/+) mouse hepatocytes. In (−/−) mouse hepatocytes, K8 protein was negative and F-actin presented a coarse and irregular pattern. Ecto-ATPase, detected by enzyme histochemistry and observed by electron microscopy, was reduced in the bile canaliculi of both (+/−) and (−/−) mouse livers, in comparison with that of (+/+) mouse livers. These results reveal for the first time different microscopical findings regarding the livers of these three genotypes. They also suggest that the reduction of ecto-ATPase plays a role in the increased fragility of (+/−) and (−/−) mouse livers.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Medical electron microscopy 32 (1999), S. 122-126 
    ISSN: 1437-773X
    Schlagwort(e): Key words Small cell neuroendocrine carcinoma ; Parotid gland ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract A case of small cell neuroendocrine carcinoma of the parotid gland is presented with immunohistochemical and electron microscopic studies. Small cell neuroendocrine carcinoma is extremely rare and is often difficult to distinguish from malignant lymphoma, adenoid cystic carcinoma, and undifferentiated carcinoma. Under light microscopy, the tumor cells consisted of solid sheets and nests of small tumor cells. Immunohistochemically, they were positive for KL-1 and EMA, and focally positive for NSE and synaptophysin. Observation using an electron microscope showed membrane-bound neuroendocrine granules in some tumor cells. Histological evaluation indicated that the present case was small cell carcinoma of the parotid gland, showing a neuroendocrine variety.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Medical electron microscopy 32 (1999), S. 167-174 
    ISSN: 1437-773X
    Schlagwort(e): Key words Apoptosis ; Docetaxel ; Human leukemia cell ; DNA fragmentation ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We induced apoptosis in cells of the human leukemia cell line HL-60 using an antitumor agent, docetaxel (Taxotere), and investigated apoptosis in various aspects using in situ end-labeling (ISEL) of DNA, DNA fragmentation assay, flow cytometry, and electron microscopy. Because it inhibits depolymerization of tubulin, docetaxel is thought to arrest the cell cycle at the mitotic stage and to exert an antitumor effect. In this study, accumulation of docetaxel-treated cells at the G2/M phase was detected using flow cytometry. On ISEL of DNA, DNA fragmentation was observed at the mitotic stage. On electron microscopy, the nuclei of apoptotic cells lost their nuclear membranes, as do cells at mitosis, demonstrating that the cells were arrested mainly at the M phase in the cell cycle.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Virchows Archiv 434 (1999), S. 455-457 
    ISSN: 1432-2307
    Schlagwort(e): Key words Melanin ; Oncocytic metaplasia ; Nasopharynx ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  A 64-year-old man presented with a history of discomfort of the throat of a few weeks’ duration. Nasoscopic examination revealed multiple small, brown pigmentations at the left suprapharynx, the base of the left nasal cavity and the pharyngeal openings of the auditory tube on both sides. Microscopically, the lesion showed a glandular pattern of oncocytic epithelium with abundant pigmented granules and melanophages in the surrounding stroma. Immunohistochemically, the dendritic cells in the basal layer were positive for S-100 protein. Electron microscopic study revealed numerous fully melanized melanosomes and hypertrophied mitochondria in the oncocytic cells. Oncocytic cells do not produce melanin for themselves, melanin granules apparently being transferred from the adjacent dendritic cells to the oncocytic cells.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 200 (1999), S. 551-558 
    ISSN: 1432-0568
    Schlagwort(e): Key words Retina ; Development ; Retinal pigment epithelium ; Microglia ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Blood-borne mononuclear cells invade the developing retina via the hyaloid vasculature at the optic nerve head. Following removal of apoptotic cell debris they give rise to the network of resident microglia. The population of cells recently described in the peripheral subretinal space of developing human eyes may represent a further population of macrophages destined to become microglia. The aim of the present study was to confirm the presence of subretinal macrophages in the developing eye in other mammalian species and perform preliminary immunophenotypic analysis in rat tissues. The range of species chosen included eutherian mammals (rat and rabbit) and marsupials (wallaby and opossum). Ocular tissues from a range of developmental stages were studied by scanning electron microscopy and transmission electron microscopy. Distinctive networks of dendriform and pleomorphic macrophages were observed by scanning electron microscopy in the peripheral subretinal space of D2 rabbits, newborn and D2 rats and D75 wallaby. Transmission electron microscopic studies of D2 rabbit, newborn and D2 rat and all ages of North American opossum revealed cells with the ultrastructural features of macrophages in the peripheral subretinal space, cilio-retinal junction and between ciliary epithelial cells. Preliminary immunoperoxidase studies using a panel of anti-leukocyte monoclonal antibodies on frozen sections of rat ocular tissues (newborn, D2 and D4) revealed ED1+ Ox42+ ED2+ but Ox6– cells in the peripheral subretinal space, peripheral retina and ciliary body epithelia. The data confirms that subretinal macrophages are a feature of the developing eye in a broad range of mammalian species and immunophenotypic evidence leads the author to postulate that these cells arise from the ciliary body vasculature and may migrate into peripheral neural retina and mature into resident microglia.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 98 (1999), S. 645-650 
    ISSN: 1432-0533
    Schlagwort(e): Key words Amyotrophic lateral sclerosis ; Autopsy ; Electron microscopy ; Immunocytochemistry ; Motor ; neuron disease
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We report two autopsy cases of motor neuron disease (MND) patients with an unusual type of muscular atrophy predominantly affecting the shoulder girdle and the upper extremities with proximal dominance. Both patients are considered to be clinically categorized into the El Escorial suspected form of amyotrophic lateral sclerosis (ALS). At autopsy, they showed marked loss of spinal anterior horn cells accompanied by astrogliosis positively immunostained with anti-glial fibrillary acidic protein antibody at the cervical level. At the lumbosacral level, anterior horn neurons were relatively well preserved and Bunina bodies, ubiquitin-positive skein-like inclusions and Lewy body-like inclusions were observed in the remaining neurons. In one patient, brain stem motor neurons (nerves V, VII, XII) and motor cortex, including Betz cells, were also affected and the corticospinal tracts were degenerated at the level of the thoracic and lumbar spinal cord. Pathological findings of this patient are consistent with those of ALS. In the other patient, the motor cortex, brain stem motor nuclei and the corticospinal tracts were well preserved, which is pathologically compatible with progressive spinal muscular atrophy. These patients with such a peculiar pattern of progressive muscular atrophy should be placed in a subgroup of ALS.
    Materialart: Digitale Medien
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  • 9
    ISSN: 1432-0568
    Schlagwort(e): Key words Vomeronasal organ ; Microvilli ; Monoclonal antibody ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  The development of the rat vomeronasal organ was studied morphologically and immunocytochemically, using the monoclonal antibodies (MAbs) VOBM1, VOBM2 and VOM2 that react with the luminal surface of the vomeronasal sensory epithelium. Postnatal day (P) 7, 14, 21, 28, 35 and adult animals were examined. The vomeronasal organ and the blood vessel of the organ markedly increased in size and the vomeronasal glands increased in number between P7 and P14. At P35, the shape of the vomeronasal organ was similar to that of the adult but its size was slightly smaller. Electron microscopy showed that only a few scattered microvilli were present on supporting cells, and receptor cells were immature at P7. At P21, well-branched microvilli of the receptor cells and many microvilli of the supporting cells were observed on the luminal surface of the sensory epithelium. At P35, most apical endings of supporting cells and receptor cells were covered with numerous microvilli. Less developed areas were also present at the luminal surface of the epithelium at P35. At P7, immunoreactivities of the three antibodies were observed as discontinuous thin-layered bands only on the luminal surface of the sensory epithelium and no immunoreactivity was observed in other regions of the vomeronasal organ. Immunoreactivities of the VOBM1, VOBM2 and VOM2 increased with age and were observed as continuous thin-layered bands on the luminal surface of the epithelium by P35. These finding suggest that the development of the vomeronasal organ continues after birth and that the organ may reach maturity just before puberty (P42–49).
    Materialart: Digitale Medien
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  • 10
    ISSN: 1432-0533
    Schlagwort(e): Key words Unmyelinated fibers ; Peripheral nerve ; Electron microscopy ; Histochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Quantitation of unmyelinated fibers (UF) in peripheral nerves has classically relied upon ultrastructural morphometry. Because this method is time-consuming, it is not typically performed in routine analysis of nerve biopsies. We applied the Bodian-Luxol technique to detect unmyelinated axons by light microscopy on semithin sections from resin-embedded nerve tissue. Estimates were compared to ultrastructural counts. The staining appeared highly specific for axons. Excellent correlation was found between optic densities and the population of UF larger than 0.5 μm. The smallest profiles detected by light microscopy had a diameter close to 0.6 μm. This new technique is not a substitute for ultrastructural quantitative morphometry of UF, as very small unmyelinated axons, especially regenerating ones, can not be reliably visualized. However, it provides a valuable light microscopic method for evaluating axonal loss among UF.
    Materialart: Digitale Medien
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  • 11
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 98 (1999), S. 330-336 
    ISSN: 1432-0533
    Schlagwort(e): Key words Micropolygyria ; Electron microscopy ; Frontal lobe ; Perivascular space ; Dot-like structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We have reported breaches of glia limitans (GL)-basal lamina (BL) complex with protruding neuroglial tissue in Fukuyama-type congenital muscular dystrophy (FCMD) fetus brain and suggested that some basic deficits in the GL-BL complex may have a pivotal role in formation of micropolygyria in FCMD. We therefore investigated the cerebral GL-BL complex in seven FCMD cases (12–27 years of age), in three cases of Duchenne muscular dystrophy (17–25 years of age) and in two non-neurological controls (28 and 33 years of age). The frontal lobe cortex was examined immunocytochemically using antibodies against collagen type IV and laminin in each case, and ultrastructurally in an adult case of FCMD. In FCMD, the BL of the cortical surface was frequently breached with protruding neural tissue that ultrastructurally showed frequent synapses, neurites that had parallel arranged microtubules, and astrocytic processes. The outermost surface of this tissue was only partly lined by a BL. In the region of the gyral adhesion of micropolygyria, the perivascular space of the apparently entrapped meningeal blood vessels was occupied by neuroglial tissue, which is assumed to have invaded through the occasionally seen breaches of the perivascular GL-BL complex. Electron microscopy of the intruding tissue showed frequent synapses, microtubule-containing neurites and astrocytic processes. No breached GL-BL complex was found in any of the non-FCMD cases. These findings indicate that in FCMD, the cerebral GL-BL complex continues to have a crucial deficit with resulting breaches through which neuroglial tissue protrudes, promoting adhesion of the adjacent cerebral gyri during brain development before and after birth.
    Materialart: Digitale Medien
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  • 12
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 199 (1999), S. 459-469 
    ISSN: 1432-0568
    Schlagwort(e): Key words Differentiation ; Electron microscopy ; Histochemistry ; Microtubules ; Neurofilaments
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  The organization of the cytoskeleton has been studied during mouse differentiation in cells of the myenteric neuronal lineage. The entire gut was examined starting from day 12.5 of embryonic life (E12.5) until birth (P0). Immunocytochemistry was performed to evaluate the expression of five of the most represented neurofilaments proteins (the low, NF-L, medium, NF-M, and heavy, NF-H, molecular weight subunits, α-internexin and peripherin) and of two of the microtubule-associated proteins (MAP1 and MAP2a+2b). In parallel, the appearance in the differentiating myenteric neurons of filamentous and microtubular structures and their intracytoplasmatic distribution were observed under the electron microscope. A differential immunohistochemical expression of the structural proteins was found. Immature cells expressed α-internexin, peripherin, NF-M and MAP1 by day E12.5; α-internexin expression was strong in these cells, but gradually decreased with age and was practically absent in adulthood. Conversely, the expression of the other three proteins increased with cell differentiation and was still present in adulthood. NF-L and NF-H expression appeared later, by day E16.5, and was weak for the entire pre- and postnatal life. MAP2a+2b was never expressed. Under the electron microscope, at day E12.5 the cytoskeleton was already organized in filamentous and microtubular structures. At this age neurofilaments were few and mainly located in the cell processes, and microtubules were numerous and mainly assembled in the neuritic growth cones, together with synaptic vesicles. With ageing, neurofilaments and microtubules were ubiquitous in the neuron. Data obtained demonstrate that cytoskeletal proteins gradually accumulate in the cells of the neuronal lineage in parallel with the organization of the cytoskeletal structures, which in turn mediate important neural events by the earliest stages of murine embryonic life, including growth of nerve processes and initiation of axonal transport.
    Materialart: Digitale Medien
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  • 13
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 125 (1999), S. 19-27 
    ISSN: 1432-1106
    Schlagwort(e): Key words Nerve injury ; Nerve repair ; Retrograde reaction ; Regeneration ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Peripheral axotomy of adult cat spinal motoneurons induces a marked loss of synaptic boutons from the cell bodies and dendritic trees. The aim of the present study was to analyze the recovery of synaptic contacts in axotomized motoneurons following reinnervation into muscle. Adult cat spinal motoneurons were first deprived of their muscular contacts for 12 weeks and, then, allowed to reinnervate their target muscle. Two years later, regenerated motoneurons were labeled with horseradish peroxidase to allow quantitative ultrastructural analyses of the synaptic covering of the cell bodies and dendrites. Presynaptic boutons were classified according to their size and the shape of their synaptic vesicles. Results show that a recovery of synaptic covering occurs in the axotomized neurons after muscle reinnervation, but it affects various bouton types to different degrees. The number of S-type boutons synapsing with the soma was 70% higher after reinnervation than at 12 weeks after axotomy, while the number of F-type boutons had increased by only 13%. Compared with the normal situation, the number of S-type boutons synapsing with the proximal dendrites increased from 82% at 12 weeks after axotomy to 180% in the reinnervated state. In conclusion, in adult cat spinal motoneurons, the reestablishment of muscular contact is followed by a normalization of some of the synaptological changes induced by a prolonged state of axotomy. In certain respects restitution is incomplete, but in others it results in overcompensation.
    Materialart: Digitale Medien
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  • 14
    Digitale Medien
    Digitale Medien
    Springer
    European biophysics journal 28 (1999), S. 263-267 
    ISSN: 1432-1017
    Schlagwort(e): Key words Human liver ; Human brain ; Ferritin ; Electron microscopy ; Mössbauer spectroscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Physik
    Notizen: Abstract Human brain (globus pallidus) and liver tissues were investigated by means of electron microscopy (EM), Mössbauer spectroscopy (MS) and SQUID magnetometry techniques. Based on MS measurements, the iron present was identified to be in the ferritin-like form (61–88%) and in the form of a low-spin iron species (the balance). Its overall concentration was estimated as 1.5(3) mg in the brain and 2.4(5) mg in the liver, per gram of lyophilized tissue. The average core diameter was determined by EM measurements to be equal to 7.5(1.3) nm for the liver and 3.3(5) nm for the brain. Magnetization measurements carried out between 5 and 300 K yielded an estimation of an average blocking temperature, KT BL, as equal to 6.7 K and 8.5 K for the liver and the brain, respectively. From the dependence of KT BL on the external magnetic field it was concluded that the ferritin-like cores in the studied samples can be regarded as non-interacting particles. Finally, the uniaxial magnetic anisotropy constant was determined to be 6×103 J/m3 for the liver and 4×104 J/m3 for the brain.
    Materialart: Digitale Medien
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  • 15
    ISSN: 1432-1459
    Schlagwort(e): Key words CADASIL ; Cerebrovascular disease ; Skin biopsy ; Muscle biopsy ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a microangiopathic syndrome. Although the defective gene has been identified, genetic analysis may be effort some due to its large size and various mutations. Providing a reliable diagnostic marker would therefore be helpful. Electron microscopy has revealed characteristic electron-dense granular deposits in the basal lamina of vessels of patients with CADASIL. We investigated the sensitivity of skin and muscle biopsies for diagnosing CADASIL. We examined 30 family members of three unrelated German families affected by CADASIL. In 14 of the 21 affected individuals we performed skin and muscle biopsies; two patients were clinically asymptomatic. Under electron microscopy all muscle and skin biopsy specimens showed patches of granular and electron-dense material in the basal layer of both arterioles and capillaries. These findings confirm that general microangiopathy is a typical feature of this syndrome and is present in the early phase of the disease with or without clinical manifestation. Thus, as electron microscopy of skin biopsy specimens can establish the diagnosis of CADASIL with high certainty, it may be considered the method of first choice.
    Materialart: Digitale Medien
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  • 16
    ISSN: 1432-2307
    Schlagwort(e): Key words Rhabdomyosarcoma ; Aorta ; Immunohistochemistry ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  We report an intimal sarcoma presenting as an aortic aneurysm. A 68-year-old man suffered from chest pain and speech disturbance. Computed tomography showed a sacciform aneurysm of the aorta, which was resected, revealing a polypoid tumour measuring 1.5×2×2.5 cm projecting into the lumen. This proved to be a poorly differentiated high-grade sarcoma having morphological, immunophenotypic and ultrastructural features consistent with rhabdomyosarcomatous differentiation. Primary sarcomas of the aorta are extremely rare. Many cases have been diagnosed as ”intimal” on the basis of their site of origin, and they are not easy to classify from their histological pattern. Electron microscopy and the use of a more comprehensive panel of immunohistochemical markers should be applied in the histological classification of ”intimal” sarcoma.
    Materialart: Digitale Medien
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  • 17
    ISSN: 1432-0878
    Schlagwort(e): Key words Descending contralateral movement detector (DCMD) ; Identified neuron ; Vesicles ; Electron microscopy ; 3-D reconstruction ; Locust ; Schistocercagregaria (Insecta)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract  The descending contralateral movement detector (DCMD), an identified descending interneuron in the brain of the locust Schistocerca gregaria has been investigated by using light and electron microscopy. We describe the fine structure, distribution and numbers of synapes that it receives from another identified brain neuron, the lobular giant movement detector (LGMD), and from unidentified neurons. The DCMD dendrites emerging from the integrative segment vary in form and number between individuals and sexes but always form a flattened dendritic domain. The arborizations and the integrative segment appear to be exclusively postsynaptic. Two types of synaptic contacts (Type 1 and 2) onto the DCMD can be discerned as having either round (Type 1) or pleiomorphic synaptic vesicles (Type 2) and by large (Type 1) or small (Type 2) subsynaptic appositions. Contact zones of Type 1 synapses are smaller than those of Type 2. LGMD-synapses are of Type 1 and occur intermingled with presynaptic sites of unidentified units. Some branches of the DCMD receiving input from unidentified units are devoid of contacting LGMD processes. Synapses of both types are randomly distributed over the DCMD integrative segment and at fibres with similar sizes.Type 1 synapses are much more frequent than Type 2 synapses and their number is negatively correlated with fibre diameter. For a whole DCMD dendritic arborization, a total of 8500 active zones of chemical synapses has been calculated, including a mininum of 2250 LGMD-synapses and about 1000 Type 2 synapses. The DCMD may thus receive a considerable amount of input from as yet unidentified neurons.
    Materialart: Digitale Medien
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 296 (1999), S. 359-369 
    ISSN: 1432-0878
    Schlagwort(e): Key words Apoptosis ; Electron microscopy ; Meiosis ; Spermatocytes ; Spermatogenesis ; Testis ; TUNEL ; Mouse (10 strains)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract  Apoptosis of male germ cells is a widespread but little-understood phenomenon in many animal species. The elucidation of its mechanisms could be useful in the understanding of male infertility. We have examined the distribution of dying cells with the terminal transferase-mediated nick-end labeling (TUNEL) method and by an electron-microscopic procedure in the testes of 10 mouse strains, viz., C57BL/10 (B10), SL/NiA (SL), C57BL/6 (B6), C3H/He (C3H), BALB/c (BALB), DBA2 (DBA), CBA/J (CBA), MRL/MpJ-+/+ (M+), MRL/MpJ-lpr/lpr (lpr), and wild-type NJL mice (Mus musculus musculus). In the testes of the B10, NJL, SL, B6, C3H, BALB, DBA, and CBA mice, very few TUNEL-positive cells are distributed in the seminiferous tubules, whereas in the testes of the M+ and lpr mice, many TUNEL-positive cells, which are restricted to stage XII seminiferous tubules, have been identified. The most important finding is that many metaphases of meiotic spermatocytes show a marked TUNEL-positive reaction. Some metaphases show apoptotic morphology electron-microscopically. These results suggest that the testes of MRL strains will provide a useful model for the study of the mechanism of metaphase-specific apoptosis in meiotic spermatocytes.
    Materialart: Digitale Medien
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  • 19
    ISSN: 1432-0878
    Schlagwort(e): Key words Neuromelanin ; Neuron ; Peroxidase ; Oxygen metabolism ; High-definition light microscopy ; Electron microscopy ; Ultrastructure ; Cytochemistry ; Substantia nigra ; Lumbricusterrestris (Annelida)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Histochemical examination of 1-μm tissue sections from the dorsal nerve plexus of the earthworm, Lumbricus terrestris, reveals multiple brown intraneuronal granules. These granules contain material morphologically and histochemically consistent with neuromelanin. When viewed with transmission electron microscopy, these were seen as single membrane-enclosed biphasic granules with diameters of 370–730 nm. Exposure of L. terrestris to high-level environmental oxygen resulted in an increase in the number of neuromelanin-like pigment granules within the neurons of the circular muscle layer. As measured by ortho-phenylenediamine hydrochloride, the endogenous peroxidase activity of extracts from worms incubated in high-level environmental oxygen was 51% more than controls. The endogenous peroxidase activity was localized in situ with 3,3-diaminobenzidine (DAB) and was found to increase in and around the neuromelanin-like pigment-containing neurons within the circular muscle layer. These studies suggest that the nerve net of L. terrestris may serve as a model to study the role of neuromelanin production in oxidative stress and its relationship to endogenous peroxidases.
    Materialart: Digitale Medien
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  • 20
    ISSN: 1432-0878
    Schlagwort(e): Key words Immunohistochemistry ; Electron microscopy ; Interstitial cells of Cajal ; F4/80 ; CSF-1 ; Kit-receptor ; Mouse (op/op)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The osteopetrotic (op/op) mutant mouse possesses an inactivating mutation in the colony-stimulating factor-1 (CSF-1) gene, which results in the absence of certain macrophages and in osteopetrosis, following a lack of osteoclasts. Studies of the op/op mouse indicate that CSF-1-dependent tissue macrophages may belong to a trophic and/or scavenger subpopulation, which through their effect on other cell types can significantly affect tissue functions, and that cells which are CSF-1 independent have antigen presentation and immunological functions.We have previously identified a cell system of regularly distributed macrophages in the muscularis externa of the small intestine and wanted to extend these studies to the op/op mouse.The present investigations with light- and electron-microscopic methods using fluorescent dextran, methylene blue and immunohistochemistry (F4/80, anti-kit receptor, anti-CD3, anti-CD45R/B220) show that macrophages are absent from the muscle layers, with only an occasional macrophage present in the subserosa. In the lamina propria and submucosa, macrophage numbers are reduced. In all other respects the muscularis externa appears normal, including normal organization and number of interstitial cells of Cajal. Control and op/op mice both lack cells expressing CD3 (T lymphocytes), CD45R/B220 (B lymphocytes) and mast cells in the muscularis externa. This leaves the muscularis externa macrophages as the most likely source of local cytokine production under such conditions as postoperative ileus and intussusception in infants, where the muscularis externa appears to be one target of cytokines. We conclude that the lack of macrophages, combined with the preservation of otherwise normal structure, will make the op/op mouse a valuable model by which to assess the functions and relative importance of the muscularis externa macrophages in relation to intestinal motility under normal and pathological conditions.
    Materialart: Digitale Medien
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  • 21
    ISSN: 1432-0878
    Schlagwort(e): Key words Caveolin ; Caveolae ; Lung ; Alveolar epithelial type I cell ; Immunocytochemistry ; Electron microscopy ; Confocal laser scanning microscopy ; Rat (CD)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Caveolae are flask-shaped invaginations of the plasmalemma which pinch off to form discrete vesicles within the cell cytoplasm. Biochemically, caveolae may be distinguished by the presence of a protein, caveolin, that is the principal component of filaments constituting their striated cytoplasmic coat. Squamous alveolar epithelial type I (ATI) cells, comprising approximately 95% of the surface area of lung alveolar epithelium, possess numerous plasmalemmal invaginations and cytoplasmic vesicles ultrastructurally indicative of caveolae. However, an ultrastructural appearance does not universally imply the biochemical presence of caveolin. This immunocytochemical study has utilised a novel application of confocal laser scanning and electron microscopy unequivocally to localise caveolin-1 to ATI cells. Further, cytoplasmic vesicles and flask-shaped membrane invaginations in the ATI cell were morphologically identified whose membranes were decorated with anti-caveolin-1 immunogold label. Coexistent with this, however, in both ATI and capillary endothelial cells could be seen membrane invaginations morphologically characteristic of caveolae, but which lacked associated caveolin immunogold label. This could reflect a true biochemical heterogeneity in populations of morphologically similar plasmalemmal invaginations or an antigen threshold requirement for labelling. The cuboidal alveolar epithelial type II cell (ATII) also displayed specific label for caveolin-1 but with no ultrastructural evidence for the formation of caveolae. The biochemical association of caveolin with ATI cell vesicles has broad implications for the assignment and further study of ATI cell function.
    Materialart: Digitale Medien
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  • 22
    ISSN: 1435-1536
    Schlagwort(e): Key words Double chain surfactants ; Aggregates ; Phase diagrams ; Lamellar phases ; Electron microscopy ; SANS
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract We present the phase diagrams and the properties of newly synthesised double-chain cationic N-alkyl-N-alkyl′-N,N-dimethylammonium bromide surfactants [C x C y DMABr (x = 12, 14 and 16; y = 10, 11, 12, 14 and 16)]. All the systems studied form liquid-crystalline lamellar phases but with different morphologies: unilamellar vesicles at low surfactant concentrations, multilamellar vesicles and tubular aggregates for surfactant concentrations between 2 and 10 wt% and at even higher concentrations planar bilayers of surfactant molecules in the classical Lα phase. The phase diagrams were determined with macroscopic and microscopic methods (polarisation microscopy, freeze-fracture transmission electron microscopy, scanning electron microscopy and differential interference contrast microscopy). The properties of the surfactant solutions were determined with differential scanning calorimetry measurements for Krafft point determination and small-angle neutron scattering measurements for interlamellar spacing and bilayer thickness. Finally, conductivity and viscosity measurements for phase characterisation were carried out.
    Materialart: Digitale Medien
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  • 23
    Digitale Medien
    Digitale Medien
    Springer
    European journal of epidemiology 15 (1999), S. 175-180 
    ISSN: 1573-7284
    Schlagwort(e): Electron microscopy ; Epidemiology ; Non-bacterial Gastroenteritis ; Oyster ; Small round structured viruses (SRSVs)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract From 1987 to 1992, 18 outbreaks of acute non-bacterial gastroenteritis occurred in Kyushu district. The most common symptoms were diarrhea, vomiting, nausea and abdominal cramp. Small round structured viruses (SRSVs) were detected in 52 (44.8%) of 116 stool samples from 17 outbreaks by the electron microscopy (EM) method, and a significant increase in the antibody level was noted in 42 (80.7%) of 52 paired serum samples from 12 outbreaks by the immune electron microscopy (IEM) method and in 18 (51.4%) of 35 samples from 8 outbreaks by the western blot (WB) method. However, according to the WB method, antigen-antibody reaction was not observed to reference antigen strips (SRSV-9/Tokyo 86-510, 63kDa) in three of the 8 outbreaks. The detected virus was regarded as an etiologic agent for these outbreaks. In four of 5 outbreaks which appeared associated with eating raw oysters, there was a close relation between SRSV infection and consumption of raw oysters.
    Materialart: Digitale Medien
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  • 24
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 277 (1999), S. 164-173 
    ISSN: 1435-1536
    Schlagwort(e): Keywords Nanostructures ; Thin films ; Vapor deposition ; Electron microscopy ; Optical properties
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Colloidal dispersions of Yb, Er and Pr have been prepared by chemical liquid deposition. The metals were cocondensed at 77 K with 2-methoxyethanol and ethanol to produce solvated metal atoms. The particle size of the dispersions was determined by transmission electron microscopy to range from 52 to 1080 Å; the particles had spherical shapes. After solvent evaporation under vacuum, active solids and amorphous powder were deposited over Cu and Al metal. Dispersion stability, particle size, UV/Vis absorption and zeta potential were studied. The solids prepared by solvent evaporation were characterized by Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The films prepared on Al were studied by scanning electron microscopy. The most stable colloid was obtained using 2-methoxyethanol: several concentrations were stable for several months and the zeta potential indicated that this colloid stability is mainly due to solvation effects. FTIR spectroscopy of the solids indicated solvent incorporation in the film. This observation was corroborated by thermal analysis. Information on the thermal stability of the films was obtained by TGA. The UV/Vis absorption spectrum was measured at several concentrations under different conditions.
    Materialart: Digitale Medien
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  • 25
    ISSN: 1434-4726
    Schlagwort(e): Key words Laryngeal cancer ; p53 ; Oncoprotein ; Ki67 ; Proliferating cell nuclear antigen (PCNA) ; DNA ploidy ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The difficult and complicated mechanism of cancer development with little knowledge about the biology of existing cancers can lead to a permanent search for new examination techniques to improve the precision of life expectancy in patients and the selection of the most efficient methods of treatment. The aim of this study was to analyze certain prognostic factors, i.e., p53, Ki67, proliferating cell nuclear antigen (PCNA), DNA ploidy and cell proliferating activity, as well as the degree of morphological differentiation and cell maturity evaluated on an ultrastructural level in patients with laryngeal cancers in connection with data obtained from follow-up examinations and the clinical course of the disease. Neoplastic tissue was taken from 120 patients with laryngeal cancers. All underwent surgical treatment, radiotherapy and combined treatment in the Department of Otolaryngology, Karol Marcinkowski University School of Medical Sciences, Poznań, Poland, and the Department of Otolaryngology – Head and Neck Surgery, Haukeland University, Bergen, Norway. Before beginning treatment all patients underwent histological verification of their neoplastic tissues. Histopathological examination proved that the majority of cases (95%) had a squamous cell carcinoma. The occurrence of changes within the lymph nodes of the neck (N) was significantly correlated with T, S, Ki67, metastases to lymph nodes, DNA ploidy, site and surgery performed. The degree of clinical progression (S) was intercorrelated with T, N, p53, Ki67, PCNA, DNA ploidy, site and laryngectomy. The occurrence of oncoprotein p53 in neoplastic cells was measured by the staining degree of their nuclei and was correlated with T, S, DNA ploidy, metastases to lymph nodes, PCNA and site. The degree of staining of neoplastic cells for the nuclear antigen Ki67 was correlated to T, N, G, S, DNA ploidy, metastases to lymph nodes and surgical treatment. The proliferative antigen PCNA in the examined population of patients was intercorrelated with T, p53, Ki67, metastases to lymph nodes and surgical treatment. The results obtained from DNA flow cytometry could be associated with N, G, p53, Ki67 and metastases to lymph nodes. On the basis of the results obtained, the techniques suggested for the morphological and biological evaluation of neoplastic cells in cancer of the larynx should include TNM classification + G + DNA + p53 + Ki67.
    Materialart: Digitale Medien
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  • 26
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 138 (1972), S. 255-264 
    ISSN: 1432-0568
    Schlagwort(e): Myogenesis ; Cell surface material ; Cell contact ; Culture ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Cell surface material and contact specializations were observed in embryonic chick skeletal muscle cells at early stages (prior to fusion) in monolayer culture. Ruthenium red-staining surface material was largely absent after prior treatment with trypsin. During reorganization into a tissue pattern dense staining amorphous material was seen at the cell surfaces and in the extracellular spaces of clustered cells; the free surface material was clumped, that between the cells more compact. This material appeared to be mucopolysaccharide and could be involved in adhesion. Numerous close junctions (intercellular space, 25–100 Å), as well as occasional focal tight junctions (no apparent intercellular space), were observed between apposed cells. These junctions semmed related to cellular adhesion and perhaps also to electrical coupling.
    Materialart: Digitale Medien
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  • 27
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 137 (1972), S. 188-199 
    ISSN: 1432-0568
    Schlagwort(e): Pituitary gland ; Electron microscopy ; Dog
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The parenchymal cells of the pars distalis of the dog adenohypophysis were studied with the electron microscope. Criteria for the differentiation of four cell types included the size and shape of the cells and the size, shape and distribution of organelles and secretory granules. Three secretory granule-containing cells designated as I, II and III were observed. Cell type I was further divided into subtypes (Ia, Ib, Ic) on the basis of the granule size of maximal frequency. A fourth cell type (IV) contained no or only a few secretory granules. It was unique in having a highly irregular shape with cytoplasmic processes extending between the other cell types and also occasionally enclosing follicular cavities.
    Materialart: Digitale Medien
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  • 28
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 136 (1972), S. 326-335 
    ISSN: 1432-0568
    Schlagwort(e): Gallbladder ; Electron microscopy ; Epithelium ; Embryology ; Mucopolysaccharides
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The early development of the human gallbladder epithelium was studied in 25 foetuses with crown-rump (CR) lengths from 6.0 to 22.5 cm by light and scanning and transmission electron microscopy. The PAS-reaction was used to locate cellular mucosubstances. The development could be devided into previllous and villous stages by light microscopy. The incipient formation of villi was observed in the present material at the 12.5 cm stage. Electron microscopically, three stages of development in the gallbladder epithelial cells were noticed. In the first stage, only one epithelial cell type was found. The microvilli were undeveloped, and there were no secretory granules in the epithelial cells. In the second stage, the epithelial cells contained secretory granules. The other characteristics of this stage were pseudopod-like projections on the apical cell surfaces and development of microvilli into a brush border-like structure. In the third stage, the epithelium showed the same zonal construction as that of the adult gallbladder. The apical surface of the epithelial cell was convex, and the microvilli were well developed. There were no pseudopod-like projections on the apical cell surface. The secretory granules were similar to those seen in the normal epithelial cells of the adult gallbladder. Degenerating cells were sometimes seen in this stage. The PAS-reaction was positive in the second and third stages.
    Materialart: Digitale Medien
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  • 29
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 136 (1972), S. 224-248 
    ISSN: 1432-0568
    Schlagwort(e): Basket cells ; Synapses ; Electron microscopy ; Golgi method ; Inhibition ; Axons ; Dendrites
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Stellate cells were studied in rapid Golgi preparations and in electron micrographs. These small neurons can be classified on the basis of their position in the molecular layer and the patterns of their dendritic and axonal arborizations as follows: (1) superficial cells with short, contorted dendrites and a circumscribed axonal arbor (upper third of the molecular layer); (2) deep stellate cells with radiating, twisted dendrites and with long axons giving rise to thin, varicose collaterals (middle third of the molecular layer); (3) deep stellate cells with similar dendrites and long axons giving collaterals to the basket around the Purkinje cell bodies (middle third of the molecular layer). An important characteristic of the stellate cell axon is that it generates most of its collaterals close to its origin. Even in long axon cells, only a few collaterals issue from the more distant parts of the axon. These forms contrast with the basket cell, which sends out long, straighter dendrites, and an extended axon that first emits branches at some distance from its origin. Furthermore, basket cell axon collaterals are usually stout in contrast to the frail, beaded collaterals of the stellate cell axon. The two cell types are considered to be distinct. In electron micrographs stellate cells display folded nuclei and sparse cytoplasm with the characteristics usual for small neurons. Mitochondria are often the most conspicuous organelles because of their size and pleomorphism. The dendrites cannot be followed for long distances in thin sections because of their irregular caliber and course. Axons can be recognized on the basis of their appearance in Golgi preparations as short stretches of slender fibers distended at close intervals and running athwart the grid of the parallel fibers. These distensions, full of ovoid or flattened vesicles, synapse on the shafts of Purkinje cell dendrites and also on the dendrites of Golgi cells, basket cells, and other stellate cells. In all cases the synaptic complex occupies about a third of the junctional interface, the synaptic cleft is somewhat widened, and the pre- and postsynaptic dense plaques are thin and almost symmetrical. Varicosities in the parallel fibers synapse with the soma and dendrites of stellate cells. These junctions display a widened synaptic cleft and asymmetrical pre- and postsynaptic densities. Junctions with climbing fibers (Scheibel collaterals) have also been seen. The form of the stellate cell indicates that it plays a role in cerebellar circuitry different from that of the basket cell, although both cells are inhibitory. It is probably concerned with local effects on Purkinje cell dendrites within the field of its afferent parallel fibers.
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  • 30
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 139 (1972), S. 93-105 
    ISSN: 1432-0568
    Schlagwort(e): Teleost ; Heart ; Cardiogenesis ; Electron microscopy ; Development
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary An electron microscopic study has been made on the development of the heart of the plaice (Pleuronectes platessa L.) by the examination of tissue taken from fish at the stage when the heart-tube has formed right through the larval life and up two months postmetamorphosis. The process of developments of the heart is essentially the same as that in higher vertebrates but there are certain minor sequential differences with comparable chick tissue. By day 24 (ten days after hatching) the “early larval” heart has formed which is a trilaminar structure — a layer of myocardium bounded internally by endocardium and externally by epicardium. This condition lasts until the 4a (Ryland) stage with the onset of endocardial invagination into the myocardium which is the criterion distinguishing the “late larval” heart. The “late larval” heart lasts throughout metamorphosis of the larva and until two months post-metamorphosis when the total adult heart is assumed. Thus the process of cardiogenesis continues irrespective of hatching and of metamorphosis. This study supports the concept that the epicardium is derived from an extramyocardial source. No results are presented concerning the theory that, in its earliest stages, the myocardium has a secretory function in the production of cardiac jelly, or of myofibrillogenesis in the Teleost myoblast. Stellar configurations of short lengths of newly formed sarcomeres commonly radiate out from Z centres in early myocytes and it is suggested that this is a primitive feature of Teleost myogenesis. There is also a proliferation of mitochondria within the myocardial cells at metamorphosis which may be connected to the subsequent fast growth of the heart in the succeeding two months.
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  • 31
    Digitale Medien
    Digitale Medien
    Springer
    Archives of dermatological research 244 (1972), S. 273-275 
    ISSN: 1432-069X
    Schlagwort(e): Mongolian spot ; Blue naevus ; Melanocytes of connective tissue ; Electron microscopy ; Histochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Materialart: Digitale Medien
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  • 32
    Digitale Medien
    Digitale Medien
    Springer
    Archives of dermatological research 244 (1972), S. 524-526 
    ISSN: 1432-069X
    Schlagwort(e): Electron microscopy ; Allergic contact dermatitis ; Lymphocytes ; Macrophages
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Materialart: Digitale Medien
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  • 33
    Digitale Medien
    Digitale Medien
    Springer
    Archives of dermatological research 244 (1972), S. 536-540 
    ISSN: 1432-069X
    Schlagwort(e): Collagen and auto-immune diseases ; Endoplasmatic tubular structures ; Paramyxovirus-like-structures ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Materialart: Digitale Medien
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  • 34
    Digitale Medien
    Digitale Medien
    Springer
    Archives of dermatological research 244 (1972), S. 540-542 
    ISSN: 1432-069X
    Schlagwort(e): Argyria ; Electron microscopy ; Basallamina ; Elastica ; Skin appendages
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Materialart: Digitale Medien
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  • 35
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular medicine 50 (1972), S. 552-556 
    ISSN: 1432-1440
    Schlagwort(e): Plasma cells ; Filaments ; Bence-Jones Plasmocytoma ; Synthesis of immunoglobulins ; Electron microscopy ; Plasmazellen ; Filamente ; Bence-Jones Plasmocytom ; Immunglobulinsynthese ; Elektronenmikroskopie
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Plasmazellen einer Patientin mit einem Bence-Jones Plasmocytom (BJP) gutartigen Verlaufs zeigten im Ergastoplasma zylindrische Formationen, die aus granuliertem Reticulum und Grundplasma bestehen. In den Grundplasmaschichten liegen zirkulär geordnete filamentöse Strukturen verschiedener Ausprägung. Bei starker Entwicklung des filamentösen Materials bilden sich kristallgitterartige Gefüge. Die Strukturen im Grundplasma sind nur nach doppelter Fixierung in Aldehyden und Osmiumtetroxyd zu erkennen. Sie waren nicht in Plasmazellen 4 weiterer Patienten mit anderen Myelomtypen nachweisbar. Die Beobachtungen werden in bezug auf die Biosynthese der Immunglobuline diskutiert.
    Notizen: Summary The ground substance of plasma cells of a Bence-Jones plasmocytoma with benign clinical course in a 55 year old female patient showed “cylindrical” formations composed of rough surfaced endoplasmic reticulum and ground substance. In the ground substance filamentous structures can be seen, sometimes showing a crystalline pattern. The filaments can only be demonstrated after double fixation in aldehydes and osmium tetroxyde. In the plasma cells of four patients with myeloma other than Bence-Jones plasmocytoma, similar structures could not be demonstrated. This observation is discussed regarding the biosynthesis of immunoglobulins.
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  • 36
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 123 (1972), S. 47-54 
    ISSN: 1432-0878
    Schlagwort(e): Neurosecretion ; Neurohypophysis ; Exocytosis ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung 1. Elektronenmikroskopische Untersuchungen an der Neurohypophyse von Ratte und Forelle ergeben, daß sich eine Exocytose von Elementargranula an den Endigungen der neurosekretorischen Fasern nur selten abspielt. Es wird daher angenommen, daß die Abgabe von Hormonen in der Neurohypophyse in der Regel nach dem Muster des „membrane-release“ abläuft. 2. Die Exocytose wird nicht durch eine unmittelbare tangentiale Fusion der Membran des Elementargranulums mit dem Plasmalemm der Nervenendigung (Axolemm) eingeleitet. Vor allem bei Anwendung eines Goniometertisches wird erkennbar, daß vor der Exocytose zwischen Axolemm und Membran des Granulums eine Verbindung in Gestalt eines Stieles entsteht. Die Länge dieses Verbindungsstückes entspricht etwa 2 Axolemmdicken. An der Basis des Stiels im Axolemm tritt das Stoma auf, durch das der Inhalt des Granulums bzw. dieses selbst das Axonende verläßt. 3. Die Herkunft kleiner membrannaher Vesikel (Durchmesser 500 Å) in den Endigungen neurosekretorischer Nervenfasern in der Neurohypophyse konnte nicht geklärt werden. Anzeichen einer kompensatorischen Endocytose im Sinne von Nagasawa, Douglas und Schulz (1970) wurden nicht beobachtet.
    Notizen: Summary 1. Electron microscopical investigations of the neurohypophysis in rat and trout reveal that exocytosis of neurosecretory elementary granules from the nerve endings occurs only rarely. The authors are of the opinion that hormone release in the neural lobe follows mainly the “membrane-release” pattern. 2. Exocytosis is not performed by tangential fusion of the elementary granule membrane and the plasmalemma of the nerve ending (axolemma). Administering the goniometer technique one can observe the appearance of a stalk-like structure connecting the two membranes. The basis of the stalk in the axolemma corresponds to the site of the stoma through which the core of the vesicle leaves the nerve ending. 3. The mechanism of the origin of small clear vesicles (diameter 500 Å approx.) near the axolemma of the neurosecretory terminal has not been elucidated. The authors did not observe equivalents of a compensatory endocytosis in the vicinity of granules released by exocytosis.
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  • 37
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 126 (1972), S. 348-362 
    ISSN: 1432-0878
    Schlagwort(e): Neurones ; Lumbricus ; Monoamines ; Neurosecretion ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The cerebral ganglion and the ventral nerve cord of Lumbricus terrestris have been studied with the electron microscope. The results are as follows: In the neuropile small granular vesicles (300 to 500 Å) occur in some varicose nerve fibres after fixation with potassium permanganate. This indicates the presence of noradrenaline. Sometimes only a few of the vesicles produce a positive reaction. After incubation with α-methyl-noradrenaline the numbers of nerve terminals with small granular vesicles greatly increase, indicating the presence of dopamine and/or 5-hydroxytryptamine. In this case the reaction is now complete. The number of small granular vesicles is largest in the terminal swellings. These findings are consistent with histofluorescence, chemical, and microspectrofluorometric analyses, which have demonstrated noradrenaline, dopamine, and 5-hydroxytryptamine in neurones in the central nervous system. Large granular vesicles (600 to 900 Å) are to be found in some perikarya, not identical with neurosecretory cell bodies. In this case the granular vesicles in the axon are smaller and fewer. This indicates a simultaneous proximo-distal transport and gradual decrease in size of the granular vesicles. The intraneuronal distribution of the vesicles is in agreement with the distribution of the fluorophores in the fluorescent neurones. Neurosecretory neurones are found most likely not to contain monoamines.
    Materialart: Digitale Medien
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  • 38
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 126 (1972), S. 431-436 
    ISSN: 1432-0878
    Schlagwort(e): Golgi apparatus ; Granular endoplasmic reticulum ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Numerous morphological continuities between the cisternae of the convex face of the Golgi apparatus and the granular endoplasmic reticulum (GER) were observed in post-division amebae that had divided following enucleation and renucleation. Electron microscopic radioautography with the use of 3H-uridine as a tracer indicated that perhaps the Golgi apparatus is derived from the GER. The possibility of the connections between GER and Golgi apparatus facilitating transport of materials between the two is also discussed.
    Materialart: Digitale Medien
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  • 39
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 126 (1972), S. 466-482 
    ISSN: 1432-0878
    Schlagwort(e): Macrophages ; Microtubules ; Enamel organ ; Rat ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In the enamel organ of rat incisors macrophages are present in the zone of matrix formation, the transitional zone, the enamel maturation and pigmentation zone. The macrophages accumulate adjacent to redifferentiating amelocytes in the transitional zone. The macrophages phagocytize fragments of disintegrating amelocytes. In addition to the well known complement of organelles the macrophages present an elaborated microtubular system, scattered, thick filaments, a cortical feltwork of thin filaments, and spherical nuclear bodies. The microtubules emanate from “attached” and free pericentriolar satellites and radiate aster-like towards the cell surface or into pseudopods or curve along the nuclear surface for long distances, often related to nuclear constrictions. It is suggested that the microtubular system plays a prominent role in directional movement of the macrophages. The cortical filaments, if contractile, may create the cytoplasmic flow necessary for the cell motility.
    Materialart: Digitale Medien
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  • 40
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 127 (1972), S. 116-126 
    ISSN: 1432-0878
    Schlagwort(e): Cell junctions ; Nexus ; Osmotic effects ; Fixatives ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Speicheldrüsen von Mückenlarven (Chironomus Thummi) haben eine ausgedehnte interzelluläre Kommunikation. In elektronenmikroskopischen Bildern der Speicheldrüsen wurden zwei Arten von interzellulären Verbindungen gefunden, die für die Zellkopplung verantwortlich sein könnten: septate junctions und close membrane junctions. Da die räumliche Ausdehnung der septate junctions viel größer zu sein scheint als die der close junctions, wurden erstere als wahrscheinliche Kopplungsstrukturen angesehen. Es gibt jedoch Hinweise, daß die Strukturen, welche die Zellkopplung bewirken, sehr labil sind. Unter den Faktoren, die zu einer Unterbrechung der zellulären Kommunikationen führen können, sind auch osmotische Effekte. Um mögliche Einflüsse dieser Art auf die Ultrastruktur zu verhindern, wurden die Drüsen für die mikroskopische Inspektion in isoosmotischen Lösungen fixiert. Unter diesen Bedingungen lassen sich ausgedehnte Membrankontakte vom nexus-Typ zwischen den Drüsenzellen erkennen. Ihre Ausdehnung scheint ebenso groß zu sein wie die der septate junctions. Es besteht nach diesen Befunden die Möglichkeit, daß wie in anderen kommunizierenden Zellsystemen, so auch in Speicheldrüsen die interzelluläre Kommunikation durch nexus bewirkt wird.
    Notizen: Summary Cells ofChironomus salivary glands communicate through intercellular connections of high permeability. Electron micrographs of salivary glands show two kinds of junctions between the membranes of adjacent cells, which may be responsible for cell coupling: septate junctions and close membrane junctions. A large fraction of lateral cell surfaces is occupied by septate junctions, while the area of close membrane junctions appears to be very small. Consequently septate junctions have been considered as likely sites for intercellular coupling. There are however some indications that intercellular communication is provided by structures which seem to be unstable. As osmotic effects are among the factors which can disrupt cellular communications, we have tried to eliminate possible effects of the fixing solutions on the ultrastructure of intercellular connections by using isoosmotic fixatives. Under these conditions large regions of close membrane junctions of the nexus kind have been observed to occur between gland cells. They are of similar size as septate junctions. It seems to be possible that as in other communicating cell systems nexus could be the sites for intercellular coupling of salivary gland cells.
    Materialart: Digitale Medien
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  • 41
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 127 (1972), S. 526-544 
    ISSN: 1432-0878
    Schlagwort(e): Synapses ; Crustacea ; Abdominal Ganglia ; Lateral glant fibers ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The abdominal ganglia of the crayfish Astacus pallipes contain numerous vertebrate-like synapses which are characterized by presynaptic vesicles, darkened pre- and post-synaptic membranes, cleft material, and post-synaptic “fuzz”. Such synapses occur throughout the ganglia but are most easily found dorsally, where the neuropile is relatively coarse. The neuropile is far from homogeneous. Regional variations in fiber size, in degree of profile tortuosity, and in kind, magnitude, and distribution of vesicular content result in conspicuous textural variations. The structural polarity of synapses between the lateral giant fibers and other neurons is consistent with known physiological polarity and, hence, validates our criteria for recognition of synapses within the ganglion.
    Materialart: Digitale Medien
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  • 42
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 128 (1972), S. 42-57 
    ISSN: 1432-0878
    Schlagwort(e): Microglia ; Pericytes ; Cerebral cortex (cat) ; Transformation ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Capillaries, pericytes and microglial cells in layer I of the cerebral cortex of normal adult cats have been studied with electron microscopy. The data obtained in this study show that pericytes are cells which are able to transform themselves into microglial cells by virtue of an activation process in which the astrocytic neuroglia appears to play a decisive role. By virtue of its structure, its mesodermic origin and its function the microglia has to be distinguished clearly from the astrocytic neuroglia and the oligodendroglia.
    Materialart: Digitale Medien
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  • 43
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 128 (1972), S. 100-114 
    ISSN: 1432-0878
    Schlagwort(e): Connective tissue ; Gastropoda ; Globular cells ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Die Blasenzellen stellen ein typisches Zellelement im Bindegewebe der Gastropoden dar. Licht- und elektronenmikroskopische Untersuchungen an Cepaea nemoralis haben gezeigt, daß der größte Teil einer Blasenzelle mit einer veränderlichen Glykogenmenge angefüllt ist. Diese zentrale Glykogenansammlung verdrängt das Zytoplasma mit seinen Organellen auf den peripheren Bereich der Zelle einschließlich der Zellausläufer und einen schmalen Saum um den Zellkern. Das wichtigste Identifizierungs-merkmal der Blasenzelle ist eine sehr spezialisierte — hier als Spaltenapparat bezeichnete — Oberflächendifferenzierung. Die Auswertung von Serienschnitten hat gezeigt, daß diese Oberflächenstruktur durch eine zum Teil verzweigte Invagination des extrazellulären Raumes gebildet wird, die wiederum von der Blasenzelle durch eine mäanderförmig unterbrochene Platte abgedeckt ist. Zwischen dem Spaltenapparat der Blasenzellen und dem Reusenapparat der Podozyten der Niere scheint eine Ähnlichkeit zu bestehen.
    Notizen: Summary The globular cells are typical elements of the connective tissue of Gastropods. Light- and electronmicroscopic investigations of Cepaea nemoralis have shown, that these cells are filled with variable contents of glycogen, accumulated in the centre of the cell. This crowds the cytoplasm and the cell organelles into the peripheral area, including the cell processes and a narrow band surrounding the nucleus. The typical element of the globular cell is a special differentiation of the cell surface, the so-called “Spaltenapparat”. The three-dimensional organisation of the “Spaltenapparat” has been analysed by serial ultrathin sections. The reconstruction shows, that the “Spaltenapparat” consists of numerous branched invaginations of the extracellular space covered by very small, winding cell processes; there are tiny clefts between them. There appears to be some similarity between the “Spaltenapparat” of the globular cells and the pedicels of the podocytes of the renal glomerulus.
    Materialart: Digitale Medien
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  • 44
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 128 (1972), S. 135-138 
    ISSN: 1432-0878
    Schlagwort(e): Spinal cord ; Mouse ; Myelinated neuronal soma ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Im Thorakalmark (Hinterhornbereich) einer Wildmaus wurde ein kleines Nervenzellperikaryon beobachtet, das vollständig von einer Markscheide umhüllt war. Die Zahl der Markscheidenlamellen variierte zwischen 7 und 12. An einer Stelle konnte ein sogenanntes inneres Mesoperikaryon nachgewiesen werden. Die Bedeutung dieses zufällig erhobenen Befundes ist vorerst noch offen.
    Notizen: Summary In the thoracic cord (posterior horn region) of a wild mouse, we have observed a small nerve cell soma completely enveloped by a myelin sheath. The number of myelin lamellae varied between 7 and 12. In one place, the existence of an inner ‘mesoperikaryon’ could also be shown. The significance of this fortuitous finding has not yet been explained.
    Materialart: Digitale Medien
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  • 45
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 126 (1972), S. 53-74 
    ISSN: 1432-0878
    Schlagwort(e): Oogenesis ; Rhesus monkey ; Meiotic chromosomes ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The ovaries of foetal and neonatal rhesus monkeys have been examined with the electron microscope. The fine structure of the germ cells (oogonia; oocytes at the preleptotene, leptotene, zygotene, pachytene and diplotene stages of meiotic prophase) closely resembles that of corresponding human cells. Stages in spontaneous atresia are also described. Cytoplasmic organelles in oogonia are sparse and are grouped mainly at one pole of the nucleus, but become dispersed and more abundant as oogenesis proceeds. The nuclei of oogonia contain a random fibrillar matrix which becomes organized into threads at pre-leptotene. At leptotene these chromosomal threads each contain a dense axial “core”; during zygotene they become loosely paired in a “bouquet” arrangement and at pachytene the bivalents contain synaptinemal complexes. “Single” cores reappear at diplotene, surrounded by a complex fibrillar sheath organized into lateral projections and loops with associated granules: such chromosomes resemble those in human primordial oocytes although they are more diffuse. These findings support the view that at the diplotene stage mammalian oocytes contain chromosomes of the lampbrush type. Observations on the monkey are compared with those on other species, and the ways in which chromosomal organization may influence the radiosensitivity of oocytes is discussed.
    Materialart: Digitale Medien
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  • 46
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 129 (1972), S. 1-10 
    ISSN: 1432-0878
    Schlagwort(e): Spermatogonia ; Fish ; Annulate lamellae ; Chromatoid bodies ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Observations on annulate lamellae and chromatoid bodies in spermatogonia of the cyprinid fish Pimephales notatus have revealed several commonly occurring features heretofore unreported: These include (a) the presence of annulate lamellae in close association with chromatoid bodies; (b) the existence of a chromatoid “band” or “shell” between the nuclear envelope and some chromatoid bodies with connections among them; (c) the presence of annulate pore complexes in the absence of well developed membrane envelopes as well as in association with such envelopes; (d) the presence of material just outside the nucleus and contiguous with nuclear pores which is of a similar density and texture to that of the chromatoid bands and chromatoid bodies; (e) filamentous material between the cytoplasmic sides of nuclear pores and the chromatoid “band”, bridging a distance of approximately 1000 Å and similar threads extending a like distance between chromatoid bodies (and bands) and annulate lamellae associated with them; and (f) mitochondria closely arranged about some chromatoid bodies.
    Materialart: Digitale Medien
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  • 47
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 127 (1972), S. 127-148 
    ISSN: 1432-0878
    Schlagwort(e): Nuclear envelope ; Amphibian oocytes ; Nuclear pore complex ; Chemical nature ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In order to investigate the chemical composition of the nuclear pore complexes isolated nuclei from matureXenopus laevis oocytes were manually fractioned into nucleoplasmic aggregates and the nuclear envelopes. The whole isolation procedure takes no more than 60–90 sec, and the pore complexes of the isolated envelopes are well preserved as demonstrated by electron microscopy. Minor nucleoplasmic and cytoplasmic contaminations associated with the isolated nuclear envelopes were determined with electron microscopic morphometry and were found to be quantitatively negligible as far as their mass and nucleic acid content is concerned. The RNA content of the fractions was determined by direct phosphorus analysis after differential alkaline hydrolysis. Approximately 9% of the total nuclear RNA of the matureXenopus egg was found to be attached to the nuclear envelope. The nonmembranous elements of one pore complex contain 0.41×10−16 g RNA. This value agrees well with the content estimated from morphometric data. The RNA package density in the pore complexes (270×10−15 g/μ3) is compared with the nucleolar, nucleoplasmic and cytoplasmic RNA concentration and is discussed in context with the importance of the pore complexes for the nucleo-cytoplasmic transport of RNA-containing macromolecules. Additionally, the results of the chemical analyses as well as of the3H-actinomycin D autoradiography and of the nucleoprotein staining method of Bernhard (1969) speak against the occurence of considerable amounts of DNA in the nuclear pore complex structures.
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  • 48
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 127 (1972), S. 50-86 
    ISSN: 1432-0878
    Schlagwort(e): Salivary glands ; Drosophila, larval ; Differentiation ; Involution ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Die Entwicklung bzw. Differenzierung der larvalen Speicheldrüse vonDrosophila melanogaster wurde an genau datierten Altersstadien aus dem III. Larvenstadium, der Vorpuppe und der Puppe mit lichtmikroskopischen und elektronenmikroskopischen Methoden untersucht. Zur Vermeidung großer Streuung im physiologischen Alter der Tiere wurde eine Kulturmethode entwickelt, die es erlaubt, die Häutungen zu beobachten und zur Altersbestimmung heranzuziehen. Folgende Ergebnisse wurden erzielt: 1. Die Speicheldrüse besteht bis zur Mitte des III. Larvenstadiums morphologisch aus einem einheitlichen Zelltypus, der sehr kleine Sekretgrana (∅ 0,3 μm) bildet. Diese sammeln sich am Zellapex. Die Vermutung liegt nahe, daß es sich um ein Verdauungssekret handelt.In der 2. Hälfte des III. Larvenstadiums differenzieren sich drei Zelltypen, die hier Corpuszellen, Übergangszellen und Halszellen genannt werden. Dabei ist ein Differenzierungsgradient von distal nach proximal zu beobachten. Die distal gelegenenCorpuszellen stellen die Bildung des Verdauungssekretes in der 2. Hälfte des III. Larvenstadiums ein und bilden stattdessen ein Klebesekret. Dieses Sekret wird in Form großer Grana (∅ bis zu 10 μm) zunächst in den Zellen gespeichert und kurz vor der Pupariumbildung ins Lumen der Drüse abgegeben. Kurz nach der Pupariumbildung wird das Klebesekret aus dem Körper entlassen und dient dazu, die Tönnchenpuppe an einem trockenen Substrat anzuheften. Das Klebesekret ist PAS-positiv. Wahrscheinlich handelt es sich um ein Mucoproteid. Während des Vorpuppenstadiums bilden sich in den Corpuszellen große Vakuolen, die auf Grund der elektronenmikroskopischen Befunde als Ausdruck einer weiteren Sekretionsphase und nicht als beginnende Degeneration gedeutet werden. Die mögliche Bedeutung dieses Sekretes wird diskutiert. DieÜbergangszellen liegen zwischen den Corpuszellen und den Halszellen. Sie bilden ebenfalls Klebesekret, jedoch mit zeitlicher Verzögerung. Kurz vor der Pupariumbildung sind sie wie die Corpuszellen mit ausgereiften Klebesekretgrana beladen und von diesen nicht mehr zu unterscheiden. Die proximal gelegenenHalszellen bilden kein Klebesekret, sondern setzen die Bildung des Verdauungssekretes in der 2. Hälfte des III. Larvenstadiums fort. Während des Vorpuppenstadiums bilden sich in den Halszellen nicht die großen Vakuolen wie in den Corpuszellen. 2. Die Involution der larvalen Speicheldrüse erfolgt nach der Puppenhäutung durch Autolyseprozesse, die am distalen Ende der Drüse beginnen und innerhalb 1 Std alle Zellen mit Ausnahme der Imaginalanlage erfassen. 3. Die in dieser Untersuchung erhobenen entwicklungsgeschichtlichen Befunde anDrosophila melanogaster werden mit Beobachtungen anDrosophila virilis, D. robusta undD. hydei verglichen. Dabei wird aufgezeigt, daß die Entwicklung der larvalen Speicheldrüsen von verschiedenenDrosophila-Arten enge Parallelen aufweist. Die bisher bekannten Zusammenhänge zwischen Stoffwechselaktivitäten im Zytoplasma und Genaktivitäten (Puffmuster) an den Riesenchromosomen dieser Zellen werden diskutiert.
    Notizen: Summary The development and differentiation of the larval salivary glands ofDrosophila melanogaster have been investigated with light and electron microscopical methods. The organ has been dissected out of exactly dated stages of the III. instar larva, the prepupa and the early pupa. In order to avoid great variations in the physiological age of the animals a culture method has been developed, enabling the larval molts to be observed and used for identification of the age. The results are as follows: 1. The salivary gland of the early larva up to the middle of the III. instar period is a homogenous sack consisting of one sort of cells, in which very small secretion granules (∅ 0,3 μm) are synthesized. These secretion granules concentrate near the cellular apex. They are supposed to contain digestion enzymes. 2. In the second half of the III. larval instar period three cell types are differentiated, which are called corpus cells, transitional cells and collum cells. A gradient of differentiation from distal to proximal can be observed. 3. Thecorpus cells, located at the distal part of the gland, stop the production of digestion enzymes in the second half of the III. larval instar period and begin to synthesize a cement substance. This cement first is stored in grana (∅ up to 10 μm) inside the corpus cells. Shortly before puparium formation it is extruded into the lumen of the gland. Shortly after puparium formation it is expectorated out of the mouth, runs along the body wall and affixes the puparium to the substrate. The cement is PAS-positive, probably being a mucoproteid. In the corpus cells large vacuoles are formed during the prepupal instar period. On the basis of these electron microscopical results the vacuoles are interpreted to represent another form of a secretory product and not an equivalent of beginning degeneration. The possible function of this substance is discussed. 4. Thetransitional cells are located between the corpus cells and the collum cells. They also synthesize cement at a delayed rate, through shortly before puparium formation they are filled with cement like the corpus cells and cannot be distinguished from the latter. Thecollum cells form the most proximal part of the salivary gland. They do not produce cement but continue to synthesize digestion enzyme granules in the second half of the III. instar period. The large secretion vacuoles, found in the corpus cells during the prepupal instar period, are not synthesized in the collum cells. 5. The involution of the larval salivary gland begins after pupation and is indicated by autolytic processes, which begin at the distal end of the gland. One hour later all cells exept the imaginalanlage show signs of degeneration. 6. The course of development of the salivary glands investigated in the present study inDrosophila melanogaster is compared with similar investigations onDrosophila virilis, robusta andhydei. It is pointed out that the development of the larval salivary gland in different species ofDrosophila shows close parallels. The relationships between metabolic activities in the cytoplasm and gene physiological activities (pattern of puffs) on the giant chromosomes, as known so far, are discussed.
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  • 49
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 130 (1972), S. 70-92 
    ISSN: 1432-0878
    Schlagwort(e): Oocytes ; Different types ; Dinophilus gyrociliatus ; Cytochemistry ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Dinophilus gyrociliatus bildet zwei Oocytentypen, einen größeren, aus dem ♀♀ hervorgehen (♀-Oocyte) und einen kleineren, der sich zu ♂♂ entwickelt (♂-Oocyte). Diese beiden Oocytentypen sind von frühen Stadien der Vitellogenese an durch ihr unterschiedliches Größenwachstum zu unterscheiden. Da bei Oogonien und prävitellogenen Oocyten keine zwei unterschiedlichen Zelltypen festzustellen sind, muß man annehmen, daß die Differenzierung in ♂- und ♀-Oocyten in einem zwischen der Prävitellogenese- und der Vitellogenesephase gelegenen Übergangsstadium beginnt. Während der Prävitellogenesephase finden Zellverschmelzungen statt, aber es konnten keine Beziehungen zwischen der Fusion von Oocyten und der späteren Differenzierung nachgewiesen werden. Die ♂-Oocyte beginnt schon auf einem frühen Stadium der Vitellogenese mit der Produktion von Mucopolysaccharid-Granula, die ♀-Oocyte erst später. Diese Granula bilden nach der Ablage der Eier die Ei- oder die Kokonhülle. Die ♀-Oocyte bildet größere Proteindottergranula als die kleinere ♂-Oocyte. Eine Trennung zweier Zellsorten nach Granulagrößen läßt sich schon auf dem Übergangsstadium durchführen. Der absolute RNS-Gehalt der reifen ♀-Oocyte liegt wesentlich über dem der ♂-Oocyte; dagegen ist die Konzentration der RNS in der ♂-Oocyte höher. Die RNS-Synthese verläuft in beiden Oocytentypen parallel zur Volumenzunahme und dauert bis zum Ende der Vitellogenesephase.
    Notizen: Summary Dinophilus gyrociliatus produces two types of oocytes, a big, female producing “♀-oocyte”, and a smaller, male-producing “♂-oocyte”. They may be distinguished by their different volume from the beginning of the vitellogenic phase. Neither oogonia nor previtellogenic oocytes show two types of cells, and the beginning of differentiation in ♀-oocytes and ♂-oocytes has to be located in a connecting stage after the previtellogenic and before the vitellogenic phase. On previtellogenic stages the cells fuse and form bigger ones, but there is no connection to be found with the differentiation of the egg cells. The ♂-oocyte starts the production of mucopolysaccharid granules at an early vitellogenic stage; the ♀-oocyte does so only at later stages. These granules form the egg capsule after the eggs have been laid. The ♀-oocyte contains bigger protein yolk granules than the smaller ♂-oocyte. Already on the connecting stage it is possible to distinguish two groups of cells by the size of their granules. The ribonucleic acid content in the ♀-oocyte exceeds greatly that of the ♂-oocyte. The RNA-concentration, however, is higher in the latter one. During the vitellogenic stages the rate of RNA-synthesis in either type of oocytes parallels the increase in cell volume, the synthesis lasting up to the end of the vitellogenic phase.
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  • 50
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 131 (1972), S. 417-427 
    ISSN: 1432-0878
    Schlagwort(e): Lymphatic vessels ; Lung ; Centrioles ; Filaments ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary An electron microscopic study of the pulmonary lymphatic collecting channels and their valves in the rabbit revealed that the endothelial cells generally contain two centrioles which are almost invariably associated with one to several striated bundles of filaments. The structure of the centrioles corresponds well with that in other cell types. The filaments however were present only in endothelial cells and not in the perilymphatic connective tissue cells. The bundles consist of 2 to 6 filaments of about 40 Å diamenter and show a cross banding with a periodicity of 600 to 900 Å. They are attached at both ends or in the middle of the centriole. Their function is unknown, but they might be vestigial rootlets of rudimentary cilia of lymphatic endothelial cells.
    Materialart: Digitale Medien
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  • 51
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 132 (1972), S. 365-380 
    ISSN: 1432-0878
    Schlagwort(e): Golgi apparatus ; Membranes ; Cross-bridges ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Electron opaque cross-bridge structures span the inter- and intracisternal spaces and provide membrane-to-membrane connections between adjacent cisternae of dictyosomes of pollen tubes ofClivia andLilium. Additionally, the classic intercisternal rods, characteristic of intercisternal regions near the maturing face of dictyosomes, are connected with the adjacent membranes through similar cross-bridge elements. We suggest that these structural links are responsible for maintaining the flattened appearance of the central parts of Golgi apparatus cisternac as well as for the coherence of cisternae within the stack. Observations on other plant (e.g. microsporocytes ofCanna) and animal cells (e.g. rodent liver and hepatoma cells, newt spermatocytes) show that such an array of membrane cross-links is a universal feature of Golgi apparatus architecture. The cross-bridges appear as part of the complex “zone of exclusion” which surrounds dictyosomes, entire Golgi apparatus and Golgi apparatus equivalents in a variety of cell types.
    Materialart: Digitale Medien
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  • 52
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 130 (1972), S. 243-248 
    ISSN: 1432-0878
    Schlagwort(e): Blood vessels ; Chicken embryo ; Multivesicular structures ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung In verschiedenen Arten von Gefäß- und Mesenchymzellen in Allantois und Dottersack des Hühnchens wurden regelmäßig sog. „multivesicular structures“ beobachtet, die aus intrazellulären Aggregaten von Vesikeln (Durchmesser ca.: 800 Å) und/oder Vakuolen (Durchmesser bis 5000 Å) bestehen. Ähnliche Befunde anderer Autoren und die eigenen Ergebnisse sprechen dafür, daß es sich um das Substrat einer weitverbreiteten Zellreaktion handelt, die u.a. das morphologische Äquivalent der Sequestrierung eines z.B. im Zuge der Zelldifferenzierung überflüssig gewordenen Zytoplasmaanteils darstellt.
    Notizen: Summary In the endothelial, the media and mesenchymal cells of the vessels in the chicken's allantoic and vitelline membranes “multivesicular structure” regularly occur. They consist of aggregated vesicles and/or vacuoles (diameters ranging from 800 Å to 5000 Å) and seem to present a rather common and widespread cellular reaction, that might serve as a mechanism to sequester those parts of the cytoplasm which became superfluous e.g. during cell differentiation.
    Materialart: Digitale Medien
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  • 53
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 130 (1972), S. 338-350 
    ISSN: 1432-0878
    Schlagwort(e): Adenohypophysis ; Salmon ; Gonad maturation ; Cell types ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The fine structure of the various hormone-producing cell types (with the exclusion of the prolactin cells) in the pituitary gland (pars distalis) of migratory sockeye salmon is described. All fish were in an advanced stage of sexual maturation. In the proximal pars distalis five cell types were distinguished: growth hormone cells, ACTH cells, gonadotrops, “vesicular cells”, and “chromophobe cells”. Gonadotrops were also found throughout the rostral pars distalis. A conspicuous feature of the gonadotrops was the presence of two kinds of secretory inclusions: small electron-dense granules (200–375 mμ) and large, relatively electron-translucent globules (400–2 000 mμ). The large vesicular cells, so called because of their conspicuous vesicular endoplasmic reticulum, were numerous and often appeared to contain some small granules. It is argued that they may represent a second type of gonadotropic cell, which, in earlier stages of gonad development, contains many granules but becomes largely degranulated near the time of reproduction when the other gonadotrops (“globular gonadotrops”) abound. The chromophobes, which were smaller and far less abundant than the vesicular cells, also appeared to contain small granules (120–280 mμ). They are probably thyrotrops.
    Materialart: Digitale Medien
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  • 54
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 131 (1972), S. 347-370 
    ISSN: 1432-0878
    Schlagwort(e): Spermatozoon ; Pleurodeles ; Acrosome ; Differentiation ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Résumé L'origine et la morphogenèse des différents éléments de l'acrosome du spermatozoīde dePleurodeles waltlii ont été suivies et décrites depuis le tout début de la spermiogenèse. La formation de la vésicule acrosomienne et son évolution en une coiffe acrosomienne se fait selon le schéma classique. Son extrémité apicale se différencie tardivement en un bouton terminal et un crochet. Les trois parties de la coiffe diffèrent dans leur composition et leur structure fine. Les volumineux et complexes éléments situés sous la coiffe acrosomienne: axe, baguette puis manchon périphérique et manchon moyen, sont dépourvus de polysaccharides. Leur origine est envisagées. Ils sont comparés aux éléments situés dans l'espace sous-acrosomien des spermatozoīdes des autres vertébrés.
    Notizen: Summary The origin and the morphogenesis of the acrosome different parts ofPleurodeles spermatozoon, have been investigated and described from the early beginning spermiogenesis process. The acrosomal vesicle and acrosomal cap formation take place according to the classical scheme. The acrosomal anterior tip cap late differentiate in a blunt terminal knob and a hook. The three cap parts differ in their composition and fine structure. The large and complicated structure stretching under the acrosomal cap: axis, peripheral muff and middle muff, are devoided of polysaccharides; their origin is discussed. They are compared with the subacrosomal components lying in the other vertebrates spermatozoon subacrosomal space.
    Materialart: Digitale Medien
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  • 55
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 135 (1972), S. 211-228 
    ISSN: 1432-0878
    Schlagwort(e): Osteoclasts ; Rats ; Bone resorption ; Lysosomes ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Osteoclasts in metaphyses from young rats were systematically sectioned at different levels. Two types of osteoclasts were recognized. One type had no ruffled border while the other, and predominant type contained a ruffled border in a part of its length; some of the latter contained two ruffled borders. The closest contact between osteoclast and bone occurred at the level of the ruffled border and this bone under the border showed characteristic changes indicative of resorption. In some osteoclasts the ruffled border consisted of numerous slender cytoplasmic projections separated by very narrow spaces or channels while in other osteoclasts it was more open. The ruffled border was commonly surrounded by a transitional zone containing numerous thin filaments. The osteoclast usually had its greatest dimension at the level of the ruffled border and the cytoplasm here contained many bodies and vacuoles but a sparse endoplasmic reticulum. Away from the level of the ruffled border the cytoplasmic vacuoles and bodies were fewer while the endoplasmic reticulum was often more pronounced. Parts of the osteoclasts were usually situated close to a vessel. It is suggested that there is a correlation between the development of the ruffled border and the degree of bone resorption and that osteoclasts without a ruffled border are, at least temporarily, inactive with respect to bone resorption. The numerous cytoplasmic bodies, interpreted as lysosomes, are presumed to be important in the resorption process. The closely adjacent positioning of osteoclasts and vessels may facilitate the transport of resorption products to the blood.
    Materialart: Digitale Medien
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  • 56
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 133 (1972), S. 82-102 
    ISSN: 1432-0878
    Schlagwort(e): Echinoidea ; Colour change ; Chromatophores ; Amoeboid movement ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Für den physiologischen Farbwechsel bei Vertebraten und Evertebraten gilt die Vorstellung, daß eine Pigmentbewegung innerhalb einer formkonstanten Zelle stattfindet. Am Seeigel Centrostephanus longispinus wird nun der Nachweis einer amoeboiden Bewegung von Pigmentzellen geführt: Die Epidermis von Centrostephanus enthält große braune Chromatophoren, die bei Belichtung eine Pigmentdispersion, bei Verdunkelung eine Konzentration des Pigments zeigen. Die Chromatophoren sind außerordentlich stark verzweigte Zellen, deren Arme dicht mit Pigmentgrana erfüllt sind. Im geballten Zustand ist die allgemeine Zellform mehr oder weniger ovoid, wobei die Zellarme eingezogen und dicht um die Zellmitte angeordnet sind. Dispersion des Pigments wird hervorgerufen durch Ausstrecken der pigmentierten Zellarme in den Interzellularraum des umgebenden Gewebes. Innerhalb der Zelle werden filamentöse Elemente nachgewiesen, die vermutlich für die Zellbeweglichkeit verantwortlich sind. — Ferner wird der zelluläre Aufbau des Integuments beschrieben.
    Notizen: Summary Rapid colour changes in vertebrate and invertebrate species are considered to be due to movement of pigment granules within pigment cells of constant shape. Evidence is presented in this study to show that an amoeboid movement of chromatophores occurs in the epidermis of the Echinoderm Centrostephanus longispinus. The epidermis in this species contains large brown chromatophores, which display a dispersion of pigment on illumination and its concentration on darkening. The chromatophores are extensively branched cells, and their branches are densely packed with pigment granules. In the state of pigment concentration, the shape of the cell is more or less ovoid, and the cell branches are drawn in and closely arranged around the cell centre. Dispersion is attained by a stretching out of the pigmented cell branches into the intercellular spaces of the surrounding tissue. Within the cell, filamentous elements, which may be functional in the motility of the pigment cell, can be demonstrated.—Additionally the cellular composition of the integument is described.
    Materialart: Digitale Medien
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  • 57
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 135 (1972), S. 439-448 
    ISSN: 1432-0878
    Schlagwort(e): Neuromuscular junction ; Triturus ; Colchicine ; Axoplasmic flow ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Repeated injections of colchicine into the forearms of normal adult newts led to the disappearance of microtubules within some nerves and a concomitant loss of specialized morphological features at the neuromuscular junction. Within 2 weeks, the postsynaptic folds decreased in height and number, became flattened and eventually disappeared. In addition, nerve terminals in drug-treated animals became separated from the muscle surface and were highly congested with masses of synaptic vesicles. The present findings show that colchicine has an effect on the structural integrity of the neuromuscular junction. These effects could be direct; secondary to retraction of the nerve from the muscle surface; or the result of interference with the proper transport and/or release of neurotrophic substances.
    Materialart: Digitale Medien
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  • 58
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 135 (1972), S. 449-459 
    ISSN: 1432-0878
    Schlagwort(e): Insect brain ; Neurons ; Glia ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The fine structure of the neural sheath, glial cells and nerve cells in the brain of adult male houseflies is described. The neural sheath is composed of neural lamella and perineurium. The neural lamella consists of an external lamina and collagen-like fibrils which are embedded in an amorphous matrix. The perineurial cells form a continuous layer around the brain. On their inner surface, perineurial cells form junctional complexes with glial cell processes. A cortical cellular layer composed of neurons and glial cells surrounds the centrally located neuropil. Three types of glial cells are identified. Glial cells differ in size and in relative development and distribution of organelles. Thin processes of glioplasm completely surround the cell bodies of the neurons. Five types of neurons are described. Most of the neurons are monopolar, a few are bipolar.
    Materialart: Digitale Medien
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  • 59
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 135 (1972), S. 461-471 
    ISSN: 1432-0878
    Schlagwort(e): Centriole assembly ; Basal bodies ; Ciliogenesis ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Electron microscopy of 16 to 18 day old chick tracheas revealed that procentrioles are present near the basal ends of the recently matured centrioles and basal bodies of both ciliating and ciliated cells. Cylinders 0.1 μ in outside diameter in which densely staining walls and a central axial filament can often be detected, are present between the mature centrioles and these procentrioles. These cylinders although somewhat shorter are morphologically similar to those found earlier in the same cells in the center of procentriole clusters. So far, only one procentriole has been found in association with each cylinder and only one cylinder in association with each mature centriole or basal body. Procentrioles up to 0.18 μ in length including some with singlet microtubules in their walls have been detected. Serial sectioning indicated that in some cells up to 8% of the mature centrioles and basal bodies were associated with a cylinder and a distinct procentriole. If these procentrioles were to mature they could provide additional basal bodies for cilia after the initial wave of centriole assembly and maturation has been completed.
    Materialart: Digitale Medien
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  • 60
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 125 (1972), S. 88-107 
    ISSN: 1432-0878
    Schlagwort(e): Adenohypophysis ; Bufo bufo ; Cell differentiation ; Larval growth ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Résumé Cinq types de cellules granulées se différencient au cours de la métamorphose dans la pars distalis de l'hypophyse du têtard de Crapaud. A la prémétamorphose apparaissent les deux types de cellules protidiques, les cellules glycoprotidiques de type II et des cellules glycoprotidiques d'un type intermédiaire. Cette dernière catégorie cellulaire disparaît au climax. A la prométamorphose se différencient les cellules glycoprotidiques de type IV. Au climax s'observent les cellules glycoprotidiques de type III. Les cellules glycoprotidiques de type II sont vraisemblablement responsables de la sécrétion de l'hormone thyréotrope (TSH). Il n'est pas encore possible de préciser la fonction des autres types cellulaires. Des fibres nerveuses ont pu être observées dans la pars distalis entre les cellules granulées.
    Notizen: Summary Five granulated cell types can be distinguished in the Toad's pars distalis during larval growth. During premetamorphosis the two types of protidic cells appear, the glycoprotein containing cells of type II and an intermediary cell type which disappears during the climax. During prometamorphosis the glycoprotein cells of type IV are apparent. During the climax the glycoprotein cells of type III can be observed. The glycoprotein containing cells of type II probably produce the thyroid-stimulating-hormone (TSH). The function of the other cell types can not be specified for the moment. Nervous fibers have been observed in the pars distalis between granulated cells.
    Materialart: Digitale Medien
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  • 61
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 125 (1972), S. 289-294 
    ISSN: 1432-0878
    Schlagwort(e): Accessory optic system ; Rat ; Blood vessels ; Extracellular space ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Two types of capillaries were found in the medial terminal nucleus of the rat accessory optic system. Type one capillaries are surrounded by glial processes and lack a perivascular space, whereas the type two capillaries and arterioles show a distinct extracellular perivascular space often filled with collagen fibrils. An internal as well as an external basal lamina lines these spaces. No fenestration of the endothelium was observed.
    Materialart: Digitale Medien
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  • 62
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 125 (1972), S. 415-431 
    ISSN: 1432-0878
    Schlagwort(e): Synapses ; Rat ; Cerebral cortex ; Glutaraldehyde/E-PTA ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Synaptic junctions in intact rat cerebral cortex have been examined following glutaraldehyde fixation and phosphotungstic acid (PTA) staining. In the presynaptic ending the network has a hexagonal arrangement, while the dense projections are regularly placed along the presynaptic membrane. Cleft densities occupy the intracleft region. The postsynaptic thickening extends uninterrupted along the length of the junction. Qualitatively, the majority of junctions fall into the ‘discontinuous-continuous’ category, in which the internal coat of the presynaptic membrane together with its associated dense projections is discontinuous along the length of the junction, whereas the postsynaptic thickening is continuous. By contrast, a small number of junctions are ‘continuous-continuous’. In an attempt to analyze the junctions quantitatively, nine indices were measured. Histograms of the size distributions of seven of these appear to be bimodal, and from this it is concluded that two junction populations may be distinguishable on quantitative grounds. It is also shown that the distance separating dense projections at the presynaptic membrane is of the order of 10–15 nm. This surprisingly low value has consequences for current ideas on the relationship between synaptic vesicles and dense projections, and these are discussed at length.
    Materialart: Digitale Medien
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  • 63
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 125 (1972), S. 404-414 
    ISSN: 1432-0878
    Schlagwort(e): Renal medulla ; Rat ; Interstitial ground substance ; Fixation ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Das Interstitium des inneren Nierenmarkes von Ratten wurde nach Anwendung verschiedener Fixierungsarten und Versuchsanordnungen elektronenmikroskopisch untersucht. Neben Bindegewebszellen und kollagenen Fibrillen enthält der interstitielle Raum bandförmige, basalmembranartige Strukturen, in deren weiträumigen Maschen zwei weitere Komponenten, nämlich ein feingranuläres und feinfilamentäres Material sowie kontrastreiche, globuläre Partikel liegen. Diese beiden Formelemente stellen sich bei den verschiedenen Fixierungsarten und Versuchsanordnungen unterschiedlich dar. Bei der feingranulären und feinfilamentären Komponente handelt es sich wahrscheinlich um interstitielles Blutplasma. Diese Deutung wird gestützt durch die morphologische Ähnlichkeit mit dem Blutplasma der Blutgefäße, die unterschiedliche Darstellbarkeit nach Glutardialdehyd-und Formalinfixierung sowie durch die Befunde nach Gefäßperfusion und Nierenvenenstauung. Das Verhalten der globulären Partikel nach OsO4-Einwirkung steht in Einklang mit der schon früher gegebenen Interpretation als präzipitierte saure Mukopolysaccharide. Ihr elektronenoptisches Bild wird im Vergleich zur bekannten makromolekularen Struktur der Mukopolysaccharid-Protein-Moleküle diskutiert.
    Notizen: Summary The interstitial ground substance in the inner medulla of the rat kidney is examined electron microscopically after fixation with various fixation agents and under different experimental conditions. The papillary interstitium contains besides interstitial cells and few collagen fibrils basement membrane like material and two other components, fine granular-fibrillar elements and globular particles with heavy contrast. The appearance of the two latter interstitial components varies according to the different fixation agents used and to the experimental conditions. The fine granular and fine fibrillar material surrounds the globular particles numerously after glutardialdehyde-fixation but scarcely after formaldehyde-fixation. It increases after renal vein occlusion, but is diminished or absent, if the kidney is rinsed bloodfree. These results allow to conclude that this material represents interstitial bloodplasma. The behaviour of the globular particles after OsO4-fixation agrees well with the earlier interpretation according to which they represent precipitated acid mucopolysaccharides. Their electron microscopic appearance is discussed in comparison with the known macromolecular structure of the acid mucopolysaccharides.
    Materialart: Digitale Medien
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  • 64
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 125 (1972), S. 497-505 
    ISSN: 1432-0878
    Schlagwort(e): Chromatoid bodies ; Spermatozoa ; Cat ; Jensen's ring ; Centriole ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The first indication of differentiation of the Jensen's ring has been detected in an early stage of spermiogenesis of Felis catus Linné when the pair of centrioles takes up a position immediately beneath the plasma membrane. The chromatoid bodies appear in the early spermatid cytoplasm through the nuclear pore complex. In a more advanced stage, such bodies have been found in association with the striated columns, the distal centriole or the proximal part of flagellum and the Jensen's ring. As the spermiogenesis proceeds, the bodies have decreased their size and density, and finally disappear in mature spermatozoa. The chromatoid bodies seem, therefore, to share with the centriole the capacity to form the connecting piece. As a consequence of disorganization of triplet microtubules of the centriole, a noticeable material appears in the center of lumen of the centriole to be identifiable as a distinct precursor of the central pair of axonemal complex. Microtubules are first developed as the sheath of principal piece of the sperm flagellum, originating from the plasma membrane surrounding the axonemal complex.
    Materialart: Digitale Medien
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  • 65
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 124 (1972), S. 72-75 
    ISSN: 1432-0878
    Schlagwort(e): Erythrocytes ; Monkeys ; Malaria ; Junctional apparatus ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Electron microscopy of erythrocytes infected by the malarial parasite,Plasmodium falciparum, revealed electron dense, cone-shaped excrescences (∼40 mμ in height and ∼100 mμ in width) along the plasma membrane. These excrescences form focal junctions with the plasma membrane of reticular cells of the spleen. The resulting complexes appear to be responsible for sequestration of erythrocytes infected byP. falciparum in the spleen of the host.
    Materialart: Digitale Medien
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  • 66
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 124 (1972), S. 72-75 
    ISSN: 1432-0878
    Schlagwort(e): Erythrocytes ; Monkeys ; Malaria ; Junctional apparatus ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Electron microscopy of erythrocytes infected by the malarial parasite, Plasmodium falciparum, revealed electron dense, cone-shaped excrescences (∼40 mμ in height and ∼100 mμ in width) along the plasma membrane. These excrescences form focal junctions with the plasma membrane of reticular cells of the spleen. The resulting complexes appear to be responsible for sequestration of erythrocytes infected by P. falciparum in the spleen of the host.
    Materialart: Digitale Medien
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  • 67
    ISSN: 1432-0878
    Schlagwort(e): Carotid body ; Biogenic amines ; Reserpine ; p-Chlorophenylalanine-methylester-hydrochloride ; Fluorescence microscopy ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Der Einfluß von p-Chlorphenylalanin-methylester-hydrochlorid (PCPA) und Reserpin auf die biogenen Amine des Glomus caroticum von Kaninchen wurde ultrastrukturell und fluoreszenzmikroskopisch untersucht. Die elektronenmikroskopische Analyse ergab keine eindeutigen Kriterien für arzneimittelinduzierte Veränderungen. Fluoreszenzmikroskopisch ließ sich nach Applikation von Reserpin eine ausgeprägte Senkung des Catecholamin- und Indolamin-Gehaltes und nach PCPA eine Abnahme des Serotonins erkennen.
    Notizen: Summary The effects of p-chlorophenylalanine-methylester-hydrochloride (PCPA) and reserpine on biogenic amines of the rabbit carotid body were investigated ultrastructurally and by fluorescence microscopy. The electron microscopic analysis did not indicate significantly that structural changes result from treatment with reserpine or PCPA. Fluorescence microscopy indicated that PCPA lowered serotonin, and reserpine lowered both catecholamines and indolamines.
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  • 68
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 124 (1972), S. 387-405 
    ISSN: 1432-0878
    Schlagwort(e): Adenohypophysis ; Mouse ; Follicular cells ; Marginal cells ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Follicular cells in the mouse adenohypophysis were studied electron microscopically. These elements appear to be very similar to the marginal cells that delineate both sides of the hypophyseal cleft. The mouse differs from most other species in that the follicular cells in the pars distalis and the marginal cells look completely inactive in young, intact animals. This makes the mouse exceptionally favorable for correlating morphological changes in the cells of both types with changes in the physiological state of the animal. Different treatments applied in the present investigation all induced morphological reactions in the follicular and/or marginal cells; these reactions were generally similar. Thus, morphological changes in the follicular or marginal cells should be considered as general phenomena accompanying many changes in the physiological state of the animal, rather than as a specific result of the treatment applied. In three experiments, the follicular and marginal cells were involved in the digestion of waste material from other cells. It is suggested that the morphological changes in the other experiments should also be interpreted as signs of such an activity. In the pars tuberalis of the young, intact mouse the follicular cells may show characteristics that in the pars distalis are found only under experimental conditions. Therefore, the follicular cells in this part of the hypophysis are probably in an active state.
    Materialart: Digitale Medien
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  • 69
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 127 (1972), S. 149-174 
    ISSN: 1432-0878
    Schlagwort(e): Ependyma ; Tanycytes ; Subependyma ; Rodents ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Electron microscopic data confirm the results gained with rapid Golgi preparations of adult rodent brains that tanycytes occur in clusters along the lateral wall of the third ventricle. The cytoplasmic matrix of these cells is considerably denser than that of typical ependymal cells. They have filaments and microtubules throughout their cytoplasm along with mitochondria and polysomes. At the surface is a compact group of microvilli which suggest that tanycytes might selectively absorb material from the ventricle. The tanycytes are segregated from neuropil by other tanycyte processes, by neighboring ependymal cells and by astrocytes. Yet there are gaps in this sheath. At these points tanycytes either abut upon or surround nonglial components of the neural fabric. Their cytological features and relations with the neuropil suggest that tanycytes selectively absorb material from the ventricle and release it along the basal process, primarily affecting those segments of neurons immediately adjacent to the tanycyte.
    Materialart: Digitale Medien
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  • 70
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 127 (1972), S. 483-491 
    ISSN: 1432-0878
    Schlagwort(e): Lateral preoptic area ; Hypothalamus ; Rat ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The arcuate nucleus, median eminence, and the lateral preoptic area from the brains of aldehyde-perfused male and female rats were examined by electron microscopy. In the lateral preoptic area, three neuronal types are described: a small light neuron, a larger light one, and a dark neuron resembling the larger light one in size and nuclear shape. Many myelinated axons are interposed among single neurons or neuronal pairs. The relationship of structures to each other is discussed. Several observations not previously reported are illustrated from tissue of the arcuate nucleus and median eminence.
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  • 71
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 127 (1972), S. 492-525 
    ISSN: 1432-0878
    Schlagwort(e): Spermatozoa ; Drosophila ; Testis ; Fertility ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In Drosophila melanogaster, the cyst cell that surrounds the head region of sperm bundle becomes spheroidal or ellipsoidal and is trapped by the terminal epithelium of the testicular wall during the synchronous coiling of sperm. Extensions of this cyst cell are projected caudally into the interspaces between sperm heads probably to anchor the heads. Coiling of sperm tails is initiated at the head region and proceeds by the progressive retraction of the linear portion from the apical testicular region into the coiled portion at the base. The addition of one turn of coil is accompanied by one full rotation of the sperm bundle. When coiled, normal tails are tightly packed into a hexagonal lattice, and minute tubular structures of about 150 Å in diameter occupy the space between them. Sperm with abnormal tails are separated from those with normal ones and isolated into a separate part of the cyst lumen. Acid phosphatase is involved in the dissolution of the minute tubules for the liberation of sperm from the cyst. Sperm are released leaving the major portion of the cyst cells intact. This portion contains degenerating abnormal tails and the waste products of the individualization process. This detritus is ingested by the terminal epithelium and eventually degenerates.
    Materialart: Digitale Medien
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  • 72
    ISSN: 1432-0878
    Schlagwort(e): Neurosecretory cells ; Pars intercerebralis ; Locust ; Autoradiography ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Résumé Après injection de cystéine S35, les cellules A, B, C et les neurones banaux de la pars intercerebralis chez Locusta (femelles immatures et mûres) sont radioactifs. Le taux d' incorporation de la cystéine S35 dans les cellules B est identique chez toutes les femelles et il est légèrement supérieur à celui des neurones banaux. Ces résultats confirment l'inactivité sécrétoire protéique des cellules B. Les cellules C incorporent 3 à 5 fois plus de cystéine S35 que les neurones banaux. Elles synthétisent donc une ou plusieurs protéines contenant de la cystéine ce qui réaffirme leur activité neurosécrétrice chez Locusta. Les cellules A possèdent le taux d'incorporation de cystéine S35 le plus élevé: 5 à 8 fois celui des neurones banaux. Chez toutes les femelles, les cellules A synthétisent plus de neurosécrétion et en éliminent proportionellement plus que les cellules C. La neurosécrétion A est élaborée sous sa forme figurée plus rapidement (30 min) que la neurosécrétion C (60 min). Le renouvellement de la neurosécrétion A est donc quantitativement plus important et plus rapide que celui de la neurosécrétion C. Chez les femelles immatures, les cellules A et C synthétisent plus de matériel et en éliminent proportionnellement plus que chez les femelles mûres. Le temps nécessaire à l'élaboration et à la vidange des grains de neurosécrétion A est identique chez toutes les femelles. Il en est de même pour le matériel C. Le renouvellement des neurosécrétions A et C est donc plus important chez les femelles immatures que chez les femelles mûres mais il n'est pas plus rapide. L'accumulation du matériel fuchsinophile dans les cellules A et C lors de la maturation ovarienne correspond à une réduction de leur fonction neurosécrétrice: elle résulte d'une diminution de l'activité d'élimination des cellules neurosécrétrices A et C supérieure à l'affaiblissement de leur activité de synthèse.
    Notizen: Summary After injection of 35S-cysteine, the A, B, C cells and the ordinary neurones of pars intercerebralis in Locusta — immature and mature females — are radioactive. The rate of incorporation of 35S-cysteine into the B cells is the same for all the females, and it is slightly higher than the rate of incorporation of 35S-cysteine into the ordinary neurones. These results demonstrate the proteinic secretory inactivity of the B cells. The C cells incorporate 3 to 5 times more 35S-cysteine than ordinary neurones. Thus, the C cells synthesize one protein or several proteins with cysteine; this observation confirms their neurosecretory activity in Locusta. The A cells have the highest rate of incorporation of 35S-cysteine: 5 to 8 times the one of ordinary neurones. In all the females, the A cells produce and release proportionally more neurosecretion than the C cells. The production of granules is faster in A cells (30 min) than in C cells (60 min). The turnover of the A neurosecretion is consequently higher and quicker than the C neurosecretion. In immature females, the A and C cells synthesize and release proportionally more material than in mature females. The time necessary for production and release of the A neurosecretion is the same for all the females. It is so for the C material. The turnover of the A and C neurosecretions is thus more important in immature females than in mature females but it is not more rapid. The accumulation of stainable neurosecretory material in A and C cells at the time of ovarian maturation is associated with a reduction of their neurosecretory activity: it is due to a decrease of the rate of release of the A and C cells being more important than their rate of production.
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  • 73
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 128 (1972), S. 393-405 
    ISSN: 1432-0878
    Schlagwort(e): Peripheral nerve ; Polyamines ; Autoradiography ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Mit Hilfe der Autoradiographie von Semi- und Ultradünnschnitten wurde die Verteilung der Radioaktivität nach Applikation von 3H-Putrescin im intakten und im degenerierenden N. ischiadicus der Ratte sowie in Spinalganglien untersucht. Im intakten und im geschädigten Nerven war die Radioaktivität, die zum weit überwiegenden Anteil als Spermidin und Putrescin vorkam, in allen zellulären Bestandteilen des Nerven, im Cytoplasma, in den Kernen und sehr deutlich auch in den Markscheiden, lokalisiert. Im extrazellulären Raum und über den Kollagenfibrillen war demgegenüber nur eine sehr geringe Radioaktivität festzustellen. Die physiologische Funktion von Spermidin und Putrescin im Myelin und den anderen Zellbestandteilen wird in erster Linie im Zusammenhang mit der in diesen Strukturen ebenfalls lokalisierten RNA diskutiert, da zahlreiche Hinweise für eine Rolle der Polyamine in der RNA- und Proteinsynthese vorliegen.
    Notizen: Summary The distribution of radioactivity from 3H-putrescine was studied in intact and degenerated sciatic nerves, and spinal ganglia of rats by means of high resolution autoradiography. During the first three days after the administration of the labeled putrescine, the main proportion of radioactive material in the nerves was represented by spermidine and putrescine. Both, in intact and degenerating nerves, developed silver grains were deposited in all cellular components of the nervous tissue, the myelin sheath being markedly tagged. Perineural tissue was also labeled considerably, however, there was no significant amount of label in the extracellular space and in the collagen fibrils. The possible physiological significance of putrescine and spermidine in myelin and in other cellular components of nerves is discussed.
    Materialart: Digitale Medien
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  • 74
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 129 (1972), S. 11-19 
    ISSN: 1432-0878
    Schlagwort(e): Muscle ; Invertebrates ; Sabellastarte magnifica ; Striation pattern ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary As described in other invertebrate muscles, most thick myofilaments of the dorsal longitudinal muscle of Sabellastarte magnifica appear to be obliquely arranged with respect to the longitudinal axis of the myofibrils. Some sections, however, show long bundles of myofilaments parallel to the longitudinal axis of the myofibrils. Since the oblique striation concept cannot account for such images, a different (longitudinal) arrangement is proposed for Sabellastarte which can account for all observed images. A wax and threads model built according to this arrangement has been used to demonstrate that by oblique sectioning the longitudinal model can generate a false appearance of filament obliquity.
    Materialart: Digitale Medien
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  • 75
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 129 (1972), S. 256-271 
    ISSN: 1432-0878
    Schlagwort(e): 5,6-dihydroxytryptamine (5,6-DHT) ; Chemically induced degeneration ; Electron microscopy ; Indolamine containing axons and terminals ; Rat brain
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Evidence has been obtained by electron microscopy of a direct cytotoxic effect of intraventricularly administered 5,6-dihydroxytryptamine (5,6-DHT) on unmyelinated axons in the rat brain. Ultrastructural signs of axonal damage were observed in areas rich in indolamine nerve terminals as early as 2 hrs after injection. By 6–24 hrs, characteristic and more dramatic signs of degeneration developed, involving coalescence of all axonal constituents—often in combination with a uniform osmiophilic impregnation of the axoplasm—accompanied by engulfment of the dystrophic structures by glial processes. During the next five days, the degenerating axons and axon terminals appeared to be removed by glial cell phagocytosis, whose equivalents were the inclusion of axonal residues into membrane-bound lysosome-like bodies. Concomitantly, there was a progressively increasing number of extremely large and dilated axons in all regions analysed. These axonal swellings, which have an ultramorphology similar to that of dilated stumps of mechanically severed monoamine axons, correspond most probably to proximal, dilated portions of drug-damaged axons. The present results, in combination with biochemical and fluorescence microscopical data, indicate that within a proper dose range the 5,6-DHT-induced degeneration is largely restricted to indolamine axons and axon terminals. However, unselective effects on other unmyelinated axons, on myelin, and on glial cells were observed in narrow subependymal zones close to the lateral ventricles, i.e. close to the injection cannula.
    Materialart: Digitale Medien
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  • 76
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 129 (1972), S. 278-289 
    ISSN: 1432-0878
    Schlagwort(e): Midgut epithelium ; Insects ; Development ; Metamorphosis ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The ultrastructural alterations in the anterior midgut epithelium of the fly Calliphora were investigated by electron microscopy. Nine developmental stages, from late larval to late adult, were studied. During metamorphosis, a tube is formed by proliferation of undifferentiated cells residing in cell nests in the basal part of the larval epithelium. The process of microvillus formation is described and compared with that in the embryonic stage. Differences between larval and imaginal cells were found in the rate of microvillus formation and in the occurrence of dense vesicles. The formation of a basal labyrinth coincides roughly with microvillus formation. Glycogen deposits occur mainly in the pupal stage and are almost always absent after emergence. Epithelial crypts are formed in late pupae by modification of the existing layer of cells together with a localized development of muscle fibres. In the adult stage changes may take place in the form of the cell apex, which generally assumes a more pointed shape, and in the amount of osmiophilic material, aggregating almost exclusively in the supranuclear part of the cell.
    Materialart: Digitale Medien
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  • 77
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 129 (1972), S. 328-369 
    ISSN: 1432-0878
    Schlagwort(e): Anterior pituitary ; Follicular and stellate cells ; “Réseau folliculostellaire” ; Chromophobe cells ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Résumé Dans l'hypophyse du rat, la microscopie électronique permet de mettre en évidence à l'intérieur de tous les cordons épithéliaux de la pars distalis un réseau de cellules agranulaires: les cellules stellaires et folliculo-stellaires, satellites des cellules granuleuses hormonogènes. Les cellules de ce réseau se caractérisent à la fois par la multiplicité de leurs prolongements et par leur organisation autour de cavités pour la plupart submicroscopiques, «les follicules». Les cellules folliculo-stellaires correspondent à une partie des cellules chromophobes de la microscopie photonique. La fente hypophysaire, par de nombreux caractères, semble faire partie de ce système folliculo-stellaire, dont elle pourrait représenter une région privilégiée par sa situation, ses dimensions et son contenu. L'existence des cellules folliculo-stellaires dans un grand nombre d'espèces, leurs caractères cytologiques hautement différenciés, leurs relations étroites avec le milieu intérieur interstitiel et leurs modifications en fonction de l'âge et des conditions expérimentales permettent de penser qu'elles sont étroitement attachées à la fonction glandulaire.
    Notizen: Summary Electron microscopic investigation of the rat anterior pituitary reveals, throughout the whole pars distalis, a cellular network composed of agranular cells. These cells, the stellate and folliculo-stellate cells, are satellites of the granulated secretory cells. The cells of the network are characterized both by their multiple cytoplasmic processes and by their organization around cavities, most of them submicroscopic, the “follicles”. Those cells probably represent a large part of the “chromophobe” cells previously observed by light microscopy. On account of several characters, the pituitary cleft seems to be related to the “réseau folliculo-stellaire” and could be a peculiar part of this system because of its localization, size and contents. The “réseau folliculo-stellaire” is present in numerous species, showing a typical and differentiated cytology, and close relationships with the interstitial medium. Owing to its morphology and to modifications according to age and experimental conditions, this network seems to be a system intimately involved in the glandular function.
    Materialart: Digitale Medien
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  • 78
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 129 (1972), S. 395-412 
    ISSN: 1432-0878
    Schlagwort(e): Cardiac muscle ; Sarcoplasmic reticulum ; Excitation-contraction coupling ; Electron microscopy ; Cinematography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The ascidian myocardium is composed of small striated myoepithelial cells. The sarcoplasmic reticulum (SR) of these cells was reconstructed from serial sections. T-tubules are absent, but subsarcolemmal cisternae of the SR, that may be the counterpart of terminal cisternae, form couplings with the sarcolemma. Longitudinal SR tubules, parallel to the myofilaments, are interconnected near the middle of the A-band and form a transverse collar. Cinematographic photography of spontaneous contractions in fresh myocardial preparations produced records that could be analyzed frame by frame. Contractions are typically limited to parts of the myofilament field of single cells. They are locally symmetrical with respect to Z-bands; either both A-bands on each side of a Z-band converge on it (contractions), or neither A-band moves with respect to the Z-band. It is suggested that the spontaneous contractions are the result of local Ca++ release from randomly distributed subsarcolemmal cisternae. It is proposed that the symmetry of contraction is due to a rapid sequestering of Ca++ by the SR collars at the middle of the A-bands and a possible diffusion barrier at that level.
    Materialart: Digitale Medien
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  • 79
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 129 (1972), S. 471-499 
    ISSN: 1432-0878
    Schlagwort(e): Cardiac muscle cells ; Rat ; Mitotic division ; Myofibril changes ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The ultrastructure of the myocyte at all phases of mitosis as well as of early postmitotic cells has been studied in the myocardia of 14- and 18-day rat embryos and 5- and 7-day old rats. The myofibrils remain unchanged up to the late prophase. In prometaphase the majority of Z-disks in embryo myocyte myofibrils and considerable part of these disks in myofibrils of suckling rats are drastically disintegrated. This is followed by a progressive isolation and scattering of the myofilament bundles and of the whole sarcomeres during the subsequent phases of mitosis. Thick myofilaments seem to be unchanged but thin ones become frequently poorly outlined (mainly in embryos). The sarcoplasmic reticulum, including its typically differentiated subsarcolemmal cisternae, exhibits relatively few changes during mitosis. In the early postmitotic period there is a gradual restoration of contrast-rich Z-bands, interconnecting the previously isolated sarcomeres. Patterns of this process have much in common with early stages of myofibrillogenesis (appearance of subsarcolemmal “Z-bodies”, formation of skeins of thin filaments etc.). The cleavage furrow formation is either absent or considerably retarded up to the postmitotic period. Behaviour of some other organelles during myocyte mitosis has been described. Possible mechanisms and significance of the observed phenomena are discussed.
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  • 80
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 130 (1972), S. 362-377 
    ISSN: 1432-0878
    Schlagwort(e): Lorenzinian ampullae ; Polyodon spathula ; Sensory epithelium ; Synapses ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Light and electron microscopic observations on the ampullary organs of Polyodon spathula (Chondrostei, Osteichthyes) reveal a sensory epithelium similar to that found in the Lorenzinian ampulla, an electroreceptor found in marine Elasmobranchs. The sensory cells have a very small luminal part provided with a cilium. They are innervated by many nerve endings. Each nerve fibre apparently makes synaptic contact with several sensory cells. The synaptic structure in the sensory cell is composed of a flat sheet, the outermost part of which is surrounded by 3 or 4 annuli of densely staining material. The sheet extends into a protrusion of the sensory cell, and there is a corresponding invagination in the nerve terminal. The conclusion that these organs are electroreceptors, is supported by the finding that the fish responds to the introduction of an iron tube in the aquarium, whereas a wooden rod introduced in the same way causes no response.
    Materialart: Digitale Medien
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  • 81
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 131 (1972), S. 63-75 
    ISSN: 1432-0878
    Schlagwort(e): Tooth ; Enamel organ ; Cell differentiation ; Phagocytosis ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In the transitional zone of the enamel organ (rat) some of the amelocytes perish. Their debris is phagocytized and digested by stratum intermedium cells and macrophages. These two cell types also seem to remove cytosegresomes expelled from those amelocytes which survive and redifferentiate into transporting amelocytes. Digestion of the amelocyte debris in the stratum intermedium cells is effected rapidly and completely. Degeneration of stratum intermedium cells was not observed in the transitional zone.
    Materialart: Digitale Medien
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  • 82
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 129 (1972), S. 20-39 
    ISSN: 1432-0878
    Schlagwort(e): Tentacles ; Cilia ; Rhabdopleura ; Neurociliary synapses ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The tentacle of Rhabdopleura compacta (Hemichordata) consists of two layers of cells surrounding a central coelomic cavity. The two layers of cells are separated by a cell free basement lamella. The tentacles on the arms of Rhabdopleura bear three longitudinal rows of cilia. The ciliated cells are closely associated with bundles of nerve fibres, and between some of the cells and nerve fibres there are synapses. The peripheral regions of the ciliated cells are joined to one another by desmosomes. Tonofibrils join some of these desmosomes to the kinetosomes of the cilia. The nerve fibres are confined to the ectodermal layer and the muscle cells to the layer of cells within the basement lamella. In the ectodermal layer besides ciliated cells there are mucus cells, densely pigmented cells, and green bodies. The function of these last two types of cells is secretory. Most of the epithelial cells have microvilli upon their free borders.
    Materialart: Digitale Medien
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  • 83
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 129 (1972), S. 500-507 
    ISSN: 1432-0878
    Schlagwort(e): Lymphocyte ; Blastoid transformation ; Phytohemagglutinin ; Stereology ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The morphological changes of human lymphocytes living in vitro under the influence of phytohemagglutinin (PHA) were estimated quantitatively by stereological methods. Mean volume and volume fractions for average human lymphocyte and average blastoid cell from 72-hour culture with PHA were determined. It was found that the lymphocyte volume increases on an average 3.7 times mainly because of cytoplasmic volume increment by 4.3 times. The greatest enlargement concerned endoplasmic reticulum, the nucleolus, lysosomes and mitochondria. In addition a way of correction of the error in experimentally obtained volume fractions, resulting from the exclusive use of sections involving the nucleus is presented.
    Materialart: Digitale Medien
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  • 84
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 133 (1972), S. 267-275 
    ISSN: 1432-0878
    Schlagwort(e): Turbellaria ; Receptors ; Epidermis ; Secretory cells ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Die Sinneskante des landlebenden Turbellars Bipalium kewense setzt sich aus folgenden Zellformen zusammen: Papillen und distaler Teil der Epithelfalten werden von einem versenkten Epithel bedeckt. Die distale Cytoplasmalage ist besonders dicht und durch ein tubuläres System gekennzeichnet, das offenbar aus dem Golgi-Apparat der Perikaryen hervorgegangen ist. Die Perikaryen sind tief versenkt und enthalten außer dem Kern granuläres ER, Mitochondrien, Golgi-Apparat und vor allem viel Glykogen. Die Epidermis ist zellig organisiert. In ihrem Bereich kommen drei Sekretzell-Formen vor, die ebenfalls weit in die unterlagernde Bindegewebs-Muskel-Lage hineinragen. Die Sinneskante ist durch zwei Receptor-Typen charakterisiert. Multipolare Zellen erreichen mit mehreren Dendriten die Körperoberfläche im Bereich der Papillen und dem äußeren Teil der Furchen des Kopfvorderrandes. Bipolare Zellen finden sich nur tief eingesenkt in den Sinnesgruben. In ihrem Bereich kommen keine Stützzellen vor. Außer durch die Gestalt sind beide Receptoren durch die Struktur ihrer Cilien unterschieden. Wabendesmosomen sind beiden gemeinsam.
    Notizen: Summary The sensory border of the land-dwelling turbellarian Bipalium kewense consists of the following cell types: Papillae and distal part of the epithelial folds are covered by epithelial cells, the perikarya of which lie deeply below the basal lamina. Their distal cytoplasm is particularly dense and characterized by a tubular system, which obviously originates from the Golgi apparatus. The perikarya contain beside the nucleus mitochondria, rough endoplasmic reticulum, Golgi apparatus and above all numerous glycogen particles. Within this cellular epidermis three types of secretory cells occur which also penetrate deeply into the underlying layer of connective and muscle tissues. The sensory border is marked by two types of receptor cells. In the area of the papillae and in the outer part of the furrows of the anterior rim of the head, multipolar cells extend several dendrites to the body surface. Bipolar cells have been observed only in the depth of the sensory grooves. In their surroundings no supportive cells occur. Except for their shape the sensory cells differ in the structure of their cilia. Both cell types are interconnected with neighbouring cells by comb-desmosomes.
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  • 85
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 133 (1972), S. 377-387 
    ISSN: 1432-0878
    Schlagwort(e): Subcommissural organ ; Albino rat ; Dehydration ; Cholinesterase activity ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Dehydration affected certain cytological features of the subcommissural organ in the albino rat suggesting a strong secretory stimulation of the ependymal and hypendymal cells of this organ in dehydrated animals. The cytoplasm of the secretory cells of the subcommissural organ in the dehydrated rats was filled with dilated and empty sacs and vacuoles of endoplasmic reticulum. The membrane system of the Golgi apparatus was also dilated, and more numerous vesicles and vacuoles of the Golgi complex were noticed after dehydration. In brains of the dehydrated animals, Reissner's fibre was not found in the lumen of the third ventricle, and only a few vesicles containing homogeneous secretory material were seen in the cytoplasm of the subcommissural secretory cells. In control animals, the activities of the specific and non-specific cholinesterases were localized in the cytoplasmic and nuclear membranes as well as in the rough and smooth endoplasmic reticulum. After dehydration, the activities of the specific and non-specific cholinesterases were strongly decreased.
    Materialart: Digitale Medien
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  • 86
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 133 (1972), S. 415-434 
    ISSN: 1432-0878
    Schlagwort(e): Pars intermedia ; Hereditary diabetes insipidus mice ; Hypertrophied pars intermedia ; Cell type ; Innervation ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The ultrastructure of the pars intermedia (PI) of the normal VII +/+ and hereditary nephrogenic diabetes inspidus DI Os/+ mice has been studied with particular reference to the morphology of the glandular cells and their innervation. Four types of cells were observed in both the genotypes of mice, 1) the light glandular cell, 2) the dark cell, 3) a type of cell similar to ependymal cells and 4) a small percentage of typical ACTH cells, observed mostly on the PI border of the cleft and rarely in the centre of PI. The predominant light glandular cells contain mainly two types of membrane bound granules: 1) electron dense core granules, which measure 1500–2500 Å and 2) electron lucent vesicles, which measure 3000–4000 Å in diameter. Granules of intermediate size with various density are also present in both types of mice. The electron dense core granules are predominant in DI Os/+ mice, whereas, electron lucent vesicles are predominant in the normal VII +/+ mice. Similar uniform size membrane bound electron dense granules have been observed in ACTH cells of PI and pars distalis. From earlier experimental evidences and the present observations, it is concluded that the dense core granules in PI may be synthesizing ACTH or ACTH-like substance. It is also discussed that these dense core granules may further mature and give rise to MSH in the form of electron lucent vesicles. If it is so, PI light glandular cells may have dual functions, of producing MSH and ACTH. One of the functions of ependymal-like cells, may be the transport of PI secretion. Three types of nerve endings are observed throughout the PI, making synaptic contact with the predominant cell type. The innervation is more in DI Os/+ mice than in normal mice. The classification of these nerves is according to Bargmann and co-workers 1) peptidergic neurosecretory fibers, contain mainly membrane bound dense core granules, measuring 1200 to 1800 Å, and are the classic neurosecretory granules; 2) adrenergic fibers, measuring 700–900 Å; 3) cholinergic fibers, measuring 300–400 Å. Adrenergic and cholinergic fibers are more towards the hypophysial cleft. The increased innervation, the synaptic contact, the extremely hypertrophied PI and the greater activity of its light glandular cells in the DI Os/+ mice show the PI is under the influence of the nervous system.
    Materialart: Digitale Medien
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  • 87
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 134 (1972), S. 403-410 
    ISSN: 1432-0878
    Schlagwort(e): Small intestine (rat) ; Transport of peroxidase ; Epithelium ; Histochemistry ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Bei Ratten tritt 3 min nach intravenöser Injektion von Peroxydase elektronenmikroskopisch ein entsprechendes Reaktionsprodukt im Kapillarlumen der Lamina propria des Dünndarms und an der Basalmembrangrenze der Saumepithelzellen auf. 5 min nach der Injektion finden sich im basalen Abschnitt des Darmepithels pinozytotische Bläschen mit dem Peroxydase-Reaktionsprodukt. — 10–30 min nach der Injektion erreichen die Partikel die apikalen Teile der Zelle. Sie dringen in den interzellulären Spalten bis zu den Haftplatten vor, erreichen jedoch nie das Darmlumen. Im Dünndarm existiert vermutlich auch ein der Resorption entgegengesetzter Saftstrom, der durch Peroxydase markiert werden kann.
    Notizen: Summary In rats, 3 minutes after intravenous injection of peroxidase the reaction product can be observed electronmicroscopically in the lumina of the capillaries of the small intestine as well as at the border of the basement membrane of the epithelial border cells. Pinocytotic vesicles containing peroxidase particles occur in the basal portion of the epithelium of the small intestine 5 minutes after injection. 10–30 minutes later, the peroxidase reaches the apical region of the cell. The particles infiltrate into the intercellular spaces as far as the tight junctions but never reach the intestinal lumen. In the small intestine there probably exists a flow of fluid in opposite direction to the resorption, which can be marked by peroxidase.
    Materialart: Digitale Medien
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  • 88
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 134 (1972), S. 435-438 
    ISSN: 1432-0878
    Schlagwort(e): Salt gland ; Birds ; Innervation ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The innervation of the salt gland of the goose, the duck and the swan was investigated by means of electron microscopy. Axonal swellings were observed in relationship to secretory cells as well as to central duct cells. The terminals contain synaptic and densecored vesicles. There are no specialized pre- and postsynaptic membranes.
    Materialart: Digitale Medien
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  • 89
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 134 (1972), S. 367-382 
    ISSN: 1432-0878
    Schlagwort(e): Crested newt ; Pars nervosa ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In the crested newt, the ultrastructural organization of the pars nervosa is analogous to that already known in non-mammal tetrapods. An orderly array of ependymal cells makes up the inner limiting layer while less abundant pituicytes are irregularly distributed within this organ. “Light” and “dark” pituicytes can be distinguished on the basis of the relative density of the cytoplasmic matrix and the distribution of the cell organelles. Both the ependymal cells and pituicytes are rich in dense bodies and possess extensive processes which ramify among the nerve fibers, often reaching the pericapillary space which they can line for long distances. The main components of the pars nervosa are nerve fibers and nerve terminals (type A), containing electron dense granules 1200–2000 Å in diameter together with clear vesicles averaging 250–400 Å. These fibers are likely to correspond to the aldehyde fuchsin positive neurosecretory fibers revealed by light microscopy. Differences in the granule size within the fibers and terminals lead to further recognition of two subgroups (A1 and A2). Other fibers and terminals (type B) containing clear vesicles and granular vesicles 600 to 1000 Å in diameter, possibly of aminergic type, are also encountered. These fibers are rare and can be seen only in the portion of the pars nervosa near the pars intermedia of the adenohypophysis. Lastly, fibers and terminals containing only clear vesicles ranging from 250 to 400 Å (type C) are occasionally found. Nerve endings are often formed by type A fibers on the perivascular space and on the perivascular processes of the ependymal cells and pituicytes. In agreement with recent findings available in the literature, the occurrence of synaptoid contacts between these terminals and both pituicytes and ependymal cells may confirm the active role of these cells in transport and release of neurosecretion.
    Materialart: Digitale Medien
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  • 90
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 135 (1972), S. 55-61 
    ISSN: 1432-0878
    Schlagwort(e): Test ; Difflugia ; Rhizopoda, Testacea ; Morphogenesis ; Vital observation ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Die Schale von Difflugia oviformis ist aus Idiosomen zusammengefügt, d.h. kieseligen Elementen, die in verschiedener Anzahl, Gestalt und Größe in der Zelle vorgefertigt werden. Xenosomen, etwa Quarzkörnchen oder Glassplitter, werden nur gelegentlich in die Idiosomenschicht eingebaut. Die Zellteilung beginnt mit der Morphogenese einer neuen Schale für einen der beiden Abkömmlinge. Eine cytoplasmatische Knospe quillt aus der Öffnung des alten Gehäuses. Die Idiosomen für die neue Schalenwand tauchen nach und nach aus dieser Knospe auf. Die Oberfläche der jungen Anlage erscheint zunächst wellig — die Bauelemente sind in mehreren diskontinuierlichen Lagen gestaffelt, wird jedoch gegen Ende der Morphogenese glatt, wenn die Idiosomen auf eine einzige, kontinuierliche Lage verteilt und in einem Zufalls-Mosaik miteinander verkittet sind.
    Notizen: Summary The test of Difflugia oviformis is composed of idiosomes, i.e. silicious elements, prefabricated within the cell in various shapes and sizes. Xenosomes, such as grains of quartz, are only occasionally incorporated into the mono-layer of idiosomes. Cell division begins with the morphogenesis of a new test for one of the two offsprings. A cytoplasmic bud protrudes from the aperture of the shell. The elements for the construction of the thecal wall emerge successively from this anlage. The surface of the early anlage first appears to be wrinkled or undulated—the elements being distributed in several discontinuous layers—but becomes smooth towards the end of morphogenesis, as soon as the idiosomes are arranged and glued together in a random mosaic pattern to form a single, continuous stratum.
    Materialart: Digitale Medien
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  • 91
    ISSN: 1432-0878
    Schlagwort(e): Kidney ; Rat ; Actin- and myosin-like filaments ; Tubule and interstitial cells ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary By electron microscopy, the prominent bundles of filaments occurring in the basal part of proximal and distal tubule cells and in interstitial cells of rat kidney cortex were studied in cells fixed by vascular perfusion, in glycerol-extracted cells and in glycerol-extracted cells treated with heavy meromyosin (HMM). The studies of perfusion-fixed tissue showed that the proximal tubule cells contained in their most basal part filamentous bundles oriented transversely around the tubule. The bundles consisted of trightly packed thin filaments (50–80 Å in diameter). Similar but less prominent bundles were found in distal tubule cells and in interstitial cells. The dimension of these filaments was similar to that of actin filaments and their insertion in the basal cell membrane of the tubule epithelial cells resembled the insertion of actin filaments in the cell membrane of smooth muscle cells. The studies on glycerol-extracted cells revealed that some tubule cells contained two types of filaments (60–80 Å and 130–170 Å in diameter) located side by side in the basal filamentous bundles. The dimension of the thick filaments corresponds well to the values for myosin filaments in glycerinated smooth and skeletal muscle. The studies on HMM-reacted renal tissue revealed that the thin filaments (60–80 Å) described in tubule and interstitial cells are probably actin filaments, as they formed characteristic arrowhead complexes morphologically indistinguishable from the complexes of HMM with actin filaments in smooth and striated muscle cells. Our results provide strong evidence that a two-filament contractile system, based on interaction of actin and myosin filaments, exists in renal tubule and interstitial cells. As a hypothesis it is proposed that it is changes in tonus of the basal filamentous system in the proximal tubule cells which stabilize the intratubular pressure, possibly via angiotensin.
    Materialart: Digitale Medien
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  • 92
    ISSN: 1432-0878
    Schlagwort(e): Pygidial glands ; Dytiscus marginalis ; Cell types ; Secretion ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Die Pygidialdrüsen von Dytiscus sezernieren eine Emulsion, die p-Hydroxybenzaldehyd, p-Hydroxybenzoesäuremethylester, Benzoesäure und ein Glycoproteid enthält. Ihre Loben sind aus zwei verschiedenen Arten von Drüsenzellen aufgebaut, den Kanalzellen, die die Einzelkanäle und den Sammelkanal umgeben, und den Tracheoblasten. Die chitinigen Einzelkanäle enden mit einer traubigen oder blasigen Anschwellung, die aus einer massiven inneren und einer schwammigen äußeren Wandschicht besteht, in einer Höhle der sekretorischen Zellen. Die Zahl der „Blasen“ - und „Trauben“-Zellen ist etwa gleich. Die zentrale Höhle ist von Mikrovilli umgeben, die durch Mikrofibrillen in hexagonaler Packung ausgesteift werden. Wie die Untersuchung nach Gefrierätzung zeigt, ist die konvexe Seite der Mikrovilli-Membran dichter mit Partikeln besetzt als die konkave Seite. Beide Zelltypen haben ein ausgedehntes tubuläres glattes endoplasmatisches Reticulum; freie Ribosomen und granuläre Zisternen sind selten. In den Traubenzellen ist der Golgi-Apparat besser als in den Blasenzellen entwickelt. Die zentrale Höhle der Traubenzellen enthält eine fein-flockige Substanz, die der Blasenzellen ein dichtes osmiophiles Material. Die Sekretionsmechanismen, die Beteiligung verschiedener Typen von Vesikeln und anderer Zellorganellen an der Sekretion und die Unterschiede zwischen den beiden Drüsenzelltypen werden diskutiert. Es wird angenommen, daß die Hauptkomponenten des Sekretes eccrin ausgeschieden werden.
    Notizen: Summary The pygidial glands of Dytiscus secrete an emulsion containing p-hydroxybenzaldehyde, p-hydroxybenzoate, benzoic acid, and a glycoproteid (Schildknecht, 1970). Their lobes are composed of two different types of secretory cells, channel cells (which surround a channel, draining the secretory cell, as well as the collecting channel), and of tracheoblasts. The chitinous draining channel ends in the form of either a racemous or a bulbous swelling consisting of a massive inner and a spongy outer wall layer in a cavity of the secretory cell. The number of “racemous” and “bulbous” cells is nearly the same. The central cavity is surrounded by microvilli which are stiffened by microfibrils in a hexagonal packing. After freeze etching the convex surface of the microvilli reveals more membrane particles than their concave surface. Both cell types have an extended smooth surfaced tubular endoplasmic reticulum; the amount of free ribosomes and of granular cisternae is low. In the racemous cells the Golgi apparatus is better developed than in the bulbous cells. In the racemous cells the central cavity contains a fine-fluffy substance, in the bulbous cells a dense osmiophilic material. The mode of secretion, the participation of various kinds of vesicles and other cell organelles in this process, and the differences between the two types of secretory cells are discussed. It is assumed that the main components of the secretion are released in the eccrine way.
    Materialart: Digitale Medien
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  • 93
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 135 (1972), S. 229-244 
    ISSN: 1432-0878
    Schlagwort(e): Osteoclasts ; Vacuoles ; Lysosomes ; Bone resorption ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Cytoplasmic vacuoles and bodies in the osteoclast (rat) were studied by electron microscopy. The vacuole-like structures (0.03–5 μ in diameter) may be classed as a) vacuoles b) coated vacuoles and c) invaginations. The cytoplasmic bodies vary in size from 0.02–3 μ in diameter and these may similarly be classed as a) light cytoplasmic bodies, b) dense cytoplasmic bodies, c) coated cytoplasmic bodies and d) cytoplasmic bodies containing inclusions. Both the cytoplasmic vacuoles and the bodies are limited by a triple layered membrane of about 91 Å in thickness. Their relationship to the lysosomal system and the role of this system in the osteoclast is discussed.
    Materialart: Digitale Medien
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  • 94
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 135 (1972), S. 245-273 
    ISSN: 1432-0878
    Schlagwort(e): Adrenal cortex ; Primary cultures ; ACTH ; Stereology ; Autoradiography ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary A method of cultivation involving both repeated trypsinisations (at room temperature) and explantation of the tissue fragments on polythene discs has been shown to be apt to the growth in vitro of rat adult decapsulated adreno-cortical tissue. This is the first time that the successful cultivation of such a tissue is reported. The technique and its applications are discussed. The effects of β1–24 corticotrophin (ACTH1–24) on the rat adult adrenal cultures have been examined by both electron microscopy and autoradiography. Zona fasciculata and reticularis cells grown in the absence of ACTH for long terms (15–16 days) survive and proliferate as dedifferentiated elements. If ACTH1–24 is added to the cultures, adrenocortical cells will, within 2 days, simultaneously increase their proliferation rate and differentiate. After 7 days of treatment, cortical cells exhibit not only fully differentiated but even hypertrophic morphologic features. Significant stimulations of adrenal DNA, RNA and gross protein synthesis have been found to take place at different times after the starting of the ACTH1–24 treatment. These data are discussed in relation to the findings previously reported in literature. Rat adult adrenal gland tissue cultures are proposed as a non-previously available tool for investigations into the physiopathology of the adrenal cells to be carried out in a carefully controlled environment.
    Materialart: Digitale Medien
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  • 95
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 135 (1972), S. 287-314 
    ISSN: 1432-0878
    Schlagwort(e): Sympathetic neurons ; Tissue culture ; NGF ; Fluorescence histochemistry ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary 1. Phase-contrast microscopy, time-lapse cinematography, electron microscopy and fluorescence histochemistry were used to study neurons in cultured sympathetic ganglia of rat, guinea-pig and embryo chick. 2. There was considerable variation in the morphology and size of neurons in all three species. Many neurons migrated into the outgrowth; those that migrated freely in rat and guinea-pig differed sufficiently from non-migratory neurons to allow a classification into type I (migratory) and type II (non-migratory). Type II neurons appeared to correspond to those seen in situ, but whether type I neurons represent immature or retarded neurons, or are due to culture conditions, is not clear. In the chick, no classification on this basis was possible; instead both migratory and non-migratory neurons showed a large and similar variation in nuclear size. 3. In all three species both migratory and non-migratory neurons remained viable and noradrenaline was demonstrable histochemically for eight weeks (oldest cultures studied). Species differences were found in the extent of outgrowth of nerve fibers and accessory cells. 4. Ultrastructural studies showed processes with features characteristic of sympathetic nerves in situ and of regenerating nerves. Profiles with other ultrastructural features were described and their identity discussed. 5. The action of Nerve Growth Factor (NGF) at 1 unit/ml on sympathetic nerve fibers showed that guinea-pig was the most susceptible and chick the least. In the rat and guinea-pig, NGF increased levels of noradrenaline. NGF did not alter the appearance or relative numbers of type I and II neurons in rat and guinea-pig, but did affect the size distribution of both chick migratory and non-migratory neurons; some chick neurons were insensitive to NGF.
    Materialart: Digitale Medien
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  • 96
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 135 (1972), S. 349-360 
    ISSN: 1432-0878
    Schlagwort(e): Fibroblast ; Smooth muscle cell ; Contractility ; Small intestine (rat) ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The stroma of duodenal villi of rats was studied by light- and electron microscopy. Fibroblasts are rather evenly distributed within the villus. Their branched processes embrace all blood vessels, the lacteal and the bundles of smooth muscle cells. They are connected to each other and to smooth muscle cells by “close contacts”. Unmyelinated axons are found close to the fibroblasts where they may show synapse-like formations. The fibroblasts within intestinal villi contain many dilated cisterns of rER similar to normal fibroblasts. In contrast to the latter, there are many aggregated, contractile filaments, being situated mainly below the plasma membrane and within the processes. It is suggested that fibroblasts representing a 3-dimensional contractile network may be activated by smooth muscle cells and/or by innervation. So, they seem to be involved in the diminution of the vascular and stromal spaces within the villus.
    Materialart: Digitale Medien
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  • 97
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 133 (1972), S. 399-414 
    ISSN: 1432-0878
    Schlagwort(e): Retinula ; Astacus fluviatilis ; Basilar membrane ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In the eye of Astacus fluviatilis one retinula is made up by eight retinular cells. Its length is approximately 190 μm, its diameter about 40 μm at its distal, and 30 μm at its proximal pole. The nuclear regions of the retinular cells are situated distally and partly surround the end of the crystalline tract. Proximally the retinula is embedded in a tapetal layer of about 50 μm thickness made up by cells which contain gaseous vacuoles. The fused and banded rhabdome is slender and spindle-shaped and extends in the central axis of the retinula from the end of the crystalline tract down to the basilar membrane. The rhabdome consists of microvilli of the seven pigmented main retinular cells and is enveloped by their cell bodies throughout its length. An axon originates from the seven main retinular cells about 50 μm distally of the basilar membrane. It is continuously connected with the rhabdome-forming part of the cell by a thin cytoplasmic sheet. The eighth retinular cell devoid of pigment granules is in connection with the distal end of the rhabdome and sends forth a small axon taking its course with the axons of the other retinular cells. The basilar membrane is a complex system of cells which contact the retinular cells by gap junctions, other cells which synthetize fibrils, a fibrous layer and hemocyanine filled lacunas.
    Materialart: Digitale Medien
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  • 98
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 133 (1972), S. 435-454 
    ISSN: 1432-0878
    Schlagwort(e): Oocytes ; Monkey ; Radiation damage ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary This study describes the effects of acute X-irradiation of the ovaries upon the structure of primordial follicles in mature rhesus monkeys. Doses of 1000 r to 12000 r, and post-irradiation intervals of 7 hours to 30 days were used. Oocytes in biopsies from irradiated ovaries were compared with those removed from the same ovaries prior to treatment or from contra-lateral controls. The results of the treatment were assessed using light and electron microscopy. The fine structural features of normal primordial oocytes are described, with particular reference to mitochondria and dense granular bodies. Some observations on spontaneous degenerative changes are included. Irradiated ovaries are classified into four arbitrary groups according to the severity of cellular damage visible in primordial follicles with the light microscope. Effects are more marked following higher doses and/or longer intervals; the most obvious changes are pyknosis of nuclei and accumulation of dense granules in the follicle cell cytoplasm. Early changes in oocytes are relatively difficult to detect, but lead to clumping of cytoplasmic and nuclear contents at more advanced stages of degeneration. Alterations in oocyte fine structure consist mainly in swelling and disruption of membrane-bound organelles, and condensation of nuclear and nucleolar chromatin. They thus resemble those occurring during spontaneous atresia, although the damage to follicle cells is evident much sooner after irradiation. These findings are compared with those made for species in which primordial follicles are known to be destroyed by much lower doses of X-rays than were used here. The contribution to the radiation-response made by the relative radiosensitivities of oocytes and follicle cells in different species is discussed.
    Materialart: Digitale Medien
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  • 99
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 133 (1972), S. 571-582 
    ISSN: 1432-0878
    Schlagwort(e): Brain capillaries ; Chicken ; Intercellular junctions ; Differentiation ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Résumé Au cours du développement embryonnaire du Poulet, les cellules endothéliales des bourgeons vasculaires et des capillaires néo-formés du télencéphale sont unies par des jonctions transitoires au niveau desquelles les feuillets externes des membranes plasmiques n'ont pas fusionné et sont séparés par un espace intercellulaire mesurable. Des points de fusion de ces feuillets externes apparaissent peu à peu et au hasard dans la zone du contact intercellulaire. Entre ces points persistent des espaces intercellulaires qui assurent encore la communication entre la lumière du capillaire et l'espace extracellulaire du tissu nerveux. L'adjonction de nouveaux points de fusion, entre ceux existant déjà, conduit à la disparition progressive de l'espace intercellulaire et à la formation de véritables zonulae occludentes.
    Notizen: Summary During the embryonic development of the chick, the endothelial cells of the vascular sprouts and of the newly-formed capillaries in the telencephalon are linked by transitory junctions at the level of which the external leaflets of the plasma membrane are not fused and are separated by a measurable intercellular space. Some points of fusion of these external leaflets gradually appear at random in the area of the intercellular contact. Between these points of fusion, some intercellular spaces persist which still allow the communication between the capillary lumen and the extracellular space in the nervous tissue. The adjunction of new points of fusion between the preexisting ones, leads progressively to the disappearance of these intercellular spaces and to the formation of true zonulae occludentes.
    Materialart: Digitale Medien
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  • 100
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 123 (1972), S. 1-17 
    ISSN: 1432-0878
    Schlagwort(e): Gastrodermal nerves ; Hydra pseudoligactis ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Two types of nerve cells, namely, neurosensory and neurosecretory cells have been identified and described in the gastrodermis of Hydra pseudoligactis. The morphological criteria used for the identification of gastrodermal nerves are based on those presented previously for epidermal nerves. The third type of nerve cell in the epidermis, ganglionic cells, was not observed in these studies. The distribution, function and origin of gastrodermal nerve cells are discussed briefly.
    Materialart: Digitale Medien
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