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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    International journal of legal medicine 104 (1991), S. 93-97 
    ISSN: 1437-1596
    Schlagwort(e): Diethylene glycol ; Intoxication ; Myocardium ; Myocytolysis ; Ultrastructure ; Mitochondria ; Guinea pig ; Diethylenglycol ; Intoxikation ; Myokard ; Myozytolyse ; Ultrastruktur ; Mitochondrien ; Meerschweinchen
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Rechtswissenschaft
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Das Myokard von Meerschweinchen, welche mit subletalen Mengen von Diethylenglycol über eine Zeitdauer von 2–11 Tagen gefüttert worden waren, wurde mikroskopisch und elektronenmikroskopisch untersucht. Eine Koagulationsmyozytolyse und Verlust von Myofibrillen war fleckförmig verstreut über das Myokard. Diese Veränderungen waren in den Kontrollen nicht zu beobachten. Die begleitenden ultrastrukturellen Veränderungen bestanden in Schwellung, Pleomorphie, Hyperplasie von Mitochondrien, begleitet von einer Erweiterung der interfibrillären Räume und Verlagerung, Verzerrung und Ruptur angrenzender Fibrillen.
    Notizen: Summary The myocardium of guinea pigs fed on sublethal doses of diethylene glycol (DEG) over a period of 2–11 days was examined for microscopical and ultrastructural changes. Coagulative myocytolysis and loss of myofibrils, not observed in the controls, was patchily distributed throughout the myocardium. The accompanying ultrastructural features included swelling, pleomorphism and hyperplasia of mitochondria with an associated distension of the interfibrillary spaces and a displacement, distortion and rupture of adjacent myofibrils.
    Materialart: Digitale Medien
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  • 2
    ISSN: 1432-2307
    Schlagwort(e): Bromocriptine ; Pituitary neoplasm ; Prolactin ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Conventional light microscopy, immunocyto-chemistry, electron microscopy and in situ hybridization were used to evaluate the effect of dopamine agonists (bromocriptine-LAR and bromocriptine) on the morphology of surgically removed prolactin (PRL)-producing pituitary adenomas. Dopamine agonist therapy resulted in decrease of serum PRL, clinical improvement and tumour shrinkage. Using light and electron microscopy cellular atrophy, interstitial and perivascular fibrosis were noted; in several tumours connective tissue accumulation was pronounced. The cellular response was not uniform. In some adenomas populations of large cells and small cells were distinguished. The large cells contained immunoreactive PRL and expressed the PRL gene indicating resistance to dopamine agonists. It appears that these cells retained the potential to secrete PRL and proliferate despite exposure to dopamine agonists. In the small cells, PRL immunoreactivity and PRL gene expression decreased providing evidence that both PRL release and synthesis were blocked. Small cells can persist in tumours after discontinuation of dopamine agonist medication suggesting these small cells are irreversibly suppressed and are not capable of regaining their endocrine function and proliferative capability. The formation of irreversibly suppressed PRL cells may explain why some PRL-producing adenomas do not recur after withdrawal of dopamine agonists.
    Materialart: Digitale Medien
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  • 3
    ISSN: 1432-2307
    Schlagwort(e): HLA-DR ; Phaeochromocytomas ; Paragangliomas ; Immunohistochemistry ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Twelve cases of phaeochromocytoma (PCC) and four cases of paraganglioma (PGG) were studied by immunohistochemistry and immunoelectron microscopy in order to demonstrate HLA-DR (Ia)-antigen-positive dendritic cells (IaDCs). Dense infiltration of IaDCs was detected in the majority of PCCs revealing high urinary or serum catecholamine levels, but in aggressively growing PCCs, a familial PCC and all PGGs, few IaDCs were demonstrated. Interestingly, these IaDCs were negative for S-100 protein. Although S-100-protein-positive sustentacular-like cells (SCs), morphologically similar to IaDCs, were also present, these were clearly distinguished from IaDCs by our double immunostaining method. Ultrastructurally, IaDCs had smooth or slightly indented nuclei and contained a moderate amount of endoplasmic reticulum, small mitochondria and vacuoles, extending elongated cytoplasmic processes. These results suggest that determination of the quantity of IaDCs is a highly effective method of assessing the character of PCCs, in particular, their prognosis.
    Materialart: Digitale Medien
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  • 4
    ISSN: 1432-2307
    Schlagwort(e): Cell-mediated cardiocyte injury ; Acute cardiac allograft rejection ; Mononuclear cellular infiltration ; Immunohistochemistry ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary To clarify the immune mechanism of cytotoxicity in acute cardiac allograft rejection, we observed interactions between cardiocytes and mononuclear cells using immunohistochemistry and light and electron microscopy. All allografted WKA rat hearts transplanted to F344 recipients stopped beating by the 7th day after the transplantation. The population of helper/inducer T cells (Th) and IL2R+ cells was large for the first 3 days, whereas that of cytotoxic/suppressor T cells (Tc-s) and macrophages increased from the 4th day. TheTh/Tc-s ratios were more than 2.0 until the 3rd day, then decreased to less than 1.0. In circulating T lymphocytes; theTh/Tc-s ratios were under 1.0 on the 1st, 6th and 7th days. Electron microscopically IL2R+ cells, Tc-s and macrophages were often seen in close contact with the plasma membrane of the cardiocytes. The majority of IL2R+ cells are NK cells, Tc-s andTh. Of these, the population of Tc-s was small until the 3rd day. Thus, NK cells play a pivotal role in the early stage of the rejection, and Tc-s and macrophages then aggravate cell-mediated cardiocyte injury.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Virchows Archiv 418 (1991), S. 515-522 
    ISSN: 1432-2307
    Schlagwort(e): Oesophagus ; Melanocyte ; Melanoma ; Ultrastructure ; Endoscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Four examples of an endoscopically detected oesophageal melanotic lesion were examined by light microscopy, light microscope histochemistry and transmission electron microscopy, and were compared with 13 control samples of normal oesophageal epithelium. By light microscopy, pigmented melanocytes lacking atypia and mitoses were observed amongst the keratinocytes in the basal layer of the oesophageal mucosa. Junctional activity was absent. The mechanism of pigmentation was studied and found to consist of: an increase in the number of melanocytes in the basal layer of the mucosa, an increase in the quantity of melanin in these melanocytes, transfer of melanin from melanocytes to keratinocytes and to macrophages and fibroblasts in the tunica propria. Since all the lesions demonstrated increased numbers of both melanocytes and melanosomes, the term oesophagealmelanocytosis rather thanmelanosis is suggested, to emphasise the essential character of the lesion as a cellular proliferation. The value of sampling these pigmented lesions during endoscopy is emphasised as a means of obtaining well-preserved material for the evaluation of a lesion which some authorities have viewed as a possible precursor for oesophageal malignant melanoma.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1432-2307
    Schlagwort(e): Mitochondrial cardiomyopathy ; Ultrastructure ; Cytochromec oxidase deficiency ; Ventricular tachycardia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A 30-year-old woman presented with lifethreatening ventricular tachycardia without overt heart disease. Ultrastructural investigation of endomyocardial biopsy disclosed abnormally structured and often enlarged mitochondria. Morphometry revealed the ratio of volume density of mitochondria to myofibrils to be markedly increased to 0.667 as compared with five controls (mean: 0.46; range: 0.445–0.479). Investigation of mitochondrial respiratory chain enzymes revealed a 90% reduction in activity of cytochromec oxidase. Our data suggest that mitochondrial cardiomyopathy may induce malignant ventricular arrhythmias.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Urological research 19 (1991), S. 319-322 
    ISSN: 1434-0879
    Schlagwort(e): Varicocele ; Rat, Histology ; Ultrastructure ; Temperature ; Infertility
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary With no consistent animal prototype for the study of varicocele, we set out to create a model in the rat by complete ligation of the main branch of left spermatic vein (MBSV) or by partial ligation of the left renal vein. Three months later, the histology, ultrastructure and temperature of the testis and epididymis were studied. Microscopically, spermatogenic arrest was the most frequent anomaly seen. The most frequently noted ultrastructural change of the testis was distension of smooth endoplasmic reticula in Sertoli cells. The microvilli of columnar epithelia in epididymis were sparse and showed local defects. Lesions and increased temperatures in the testis and epididymis induced by the ligation of the left MBSV were similar to those seen in partial ligation of the left renal veins, with no significant differences between left and right. Significant differences were found, however, on comparison with the controls.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 183 (1991), S. 537-544 
    ISSN: 1432-0568
    Schlagwort(e): Synovial membrane ; Development ; Ultrastructure ; Scanning electron microscopy ; Mouse
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The prenatal and postnatal development of the mouse knee joint was investigated by transmission and scanning electron microscopy. In the prenatal stage, following the appearance of a narrow intercellular cleft between two skeletal elements on the 16th fetal day, clefting extended into the lateral synovial mesenchyme. In some regions, the extension of the cleft was very rapid, but in a certain region (future fat pad region), it was somewhat slower. Macrophage-like cells appeared in the synovial mesenchyme on the 16th fetal day, and then increased in number, and were distributed as if they were clustering around the presumptive clefting zone in the future fat pad region on the 17th–18th fetal day. This suggests that macrophage-like cells may participate in joint development, as they phagocytize and remove some kinds of solid extracellular matrix, and facilitate the cleft extension. In the early postnatal stage, scanning electron microscopic observations showed that there were two different types of cell in the synovial lining. One of them exhibited a surface morphology corresponding to that of macrophages: a spherical cell body and numerous pseudopodia. The other type of cell exhibited various cell shapes with many cytoplasmic processes extending along the synovial surface.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 184 (1991), S. 47-53 
    ISSN: 1432-0568
    Schlagwort(e): Wing bud ; Endothelial cell ; Development ; Ultrastructure ; Morphometry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The microvascular endothelium of the chick wing bud at stages 22, 27, and 32 was evaluated by ultrastructural morphometry. The rationale for this study is based on the hypothesis that endothelial cells exhibit variation in structure and function during cytodifferentiation. The microvessels had a luminal diameter range such that they were classified as capillaries. The thin continuous endothelium was devoid of a basal lamina. The endothelium had a very small number of plasmalemmal vesicles; vacuoles were however present for all stages and in some cases were abundant. The temporal findings were that endothelial cell thickness increases, plasmalemmal vesicle densities decrease, and the densities of cytoplasmic vacuoles increase. The spatial results were that endothelial cells in proximal regions of the limb have a greater thickness, contain fewer vesicles and have more vacuoles than those in distal regions. In general, these results indicate that endothelial ultrastructural heterogeneity occurs within a 31/2 day timespan of wing bud development. The discussion considers the results with regard to recent reports on endothelial cell heterogeneity.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 184 (1991), S. 363-369 
    ISSN: 1432-0568
    Schlagwort(e): Taste organs ; Amphibia ; Development ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In tadpoles ofRana temporaria two successive generations of taste organs: taste buds (TBs) and taste disks were studied. The TBs are located in the apices of oral premetamorphic papillae. Each TB consists of vertically elongated receptor cells (probably taste) and supporting cells. No basal (Merkel) cells were observed there. Morphologically, two types of receptor cells have been distinguished in a TB. Complete synaptic structures were observed in the TBs between the 30th and 41st of Gosner's (1960) developmental stages, though synaptic vesicles occur already at stage 26. The taste disks consist of taste cells, supporting cells and basal cells. Dense-core synaptic vesicles occur in the gustatory cells at stage 41, but complete synaptic structures were not observed earlier than at stage 45. Synaptic junctions observed at some of the gustatory cells seem to be reciprocal (bidirectional).
    Materialart: Digitale Medien
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  • 11
    ISSN: 1432-0568
    Schlagwort(e): Tachyglossus aculeatus (echidna) ; Echidna bill ; Sensory receptors ; Electroreceptor ; Mechanoreceptor ; Trigeminal nerve ; Monotreme ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The gross anatomy and nerve supply of the bill of echidna (Tachyglossus aculeatus) is described in relation to its function as an outstanding sensory organ. The sensory innervation of the skin of the echidna snout was investigated by means of frontal serial sections, after decalcification of the specimens. A comprehensive light and electron microscopic description of the location and fine structure of cutaneous sensory receptors of the trigeminal system was made by this means. The encapsulated and non-encapsulated Ruffini receptors, the types of other free receptors in the connective tissue and the Merkel cell receptor do not differ morphologically from those of higher mammals, whereas the pacinian-like corpuscle shows a unique organization of its outer core. This is composed of large perineural cells containing a unique reticulum of parallel-orientated endoplasmic membranes. Lamellated corpuscles, seen in isolation or in association with push rods, are numerous in the snout and in the tip of the tongue of echidna. Push rod receptor organs occur in the hairless skin of the bill with a very dense array at its rostral end and in the pseudopalatal ridges. Gland duct receptors are restricted to the skin adjacent to the nostrils and the mouth opening, including the pseudopalatal plates. Only about one quarter of the total number of 400 seromucous glands receive a sensory innervation of their intraepidermal duct segment. Within each innervated gland two types of receptor terminals are identified. The distributions of the different receptor types are mapped for different regions of the skin, the mucous membrane of the nasal and oral vestibule and the tip of the tongue. The fine structure of nerve terminals is discussed from a comparative anatomical point of view, and some speculations are made about possible transduction processes that underlie the known electrophysiological properties. The sensory organs such as the “push rod” and “gland duct receptor”, and most of their sensory terminals, are less differentiated in echidna snout than in the platypus (Ornithorhynchus anatinus) bill.
    Materialart: Digitale Medien
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  • 12
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 82 (1991), S. 295-301 
    ISSN: 1432-0533
    Schlagwort(e): Hyaline inclusions ; Motor neuron disease ; Amyotrophic lateral sclerosis ; Immunocytochemistry ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary We investigated hyaline inclusion bodies (HI) immunocytochemically and ultrastructurally in six cases of sporadic motor neuron disease (MND). All HI contained large amounts of ubiquitin and some HI were stained at the core or the center with anti-neurofilament antibody, with the surrounding halo unstained. No HI were stained with antibodies raised against cytoskeletal proteins such as high-molecular weight microtubule-associated proteins and phosphorylated tau. Ultrastructurally, HI were chiefly composed of filaments measuring about 20 nm in diameter thicker than neurofilaments, and contained fine granules and frequently one or more of four characteristic profiles, i.e., small electron-dense materials resembling Bunina bodies, bundles of tubular filaments measuring approximately 20 nm in diameter, large electron-dense cores, and focal accumulations of randomly arranged neurofilaments. Hyaline inclusions can be regarded as one of the characteristic markers for sporadic MND as well as familial amyotrophic lateral sclerosis. Hyaline inclusions have a markedly heterogeneous ultrastructure and, therefore, differences in immunoreactivity with antineurofilament antibodies are not unexpected.
    Materialart: Digitale Medien
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  • 13
    ISSN: 1432-0533
    Schlagwort(e): Meningioma ; Microcystic meningioma ; Vacuolated meningioma ; Arachnoid trabecular cell ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Three cases of meningiomas which had abundant small vacuoles in the tumor tissue are reported. By electron microscopy, the tumor cells exhibited long and thin processes, the tips of which were united by desmosomes. The tumor tissue was revealed to have wide extracellular spaces which corresponded to the vacuoles observed by light microscopy. In previous literature, various terms have been used when referring to this meningioma, such as microcystic meningioma or vacuolated meningioma. Since the ultrastructure of the tumor showed similarity to that of normal arachnoid trabecular cells, we propose to call the tumor “arachnoid trabecular cell meningioma” denoting its morphological nature clearly.
    Materialart: Digitale Medien
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  • 14
    ISSN: 1432-0533
    Schlagwort(e): Galactosialidosis ; Neuronal storage disease ; Neuropathology ; Ultrastructure ; Neuronal loss
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The neuropathological findings in a 13-year-old Japanese male showing decrease of sialidase and β-galactosidase activities are reported. The patient was the product of normal pregnancy to consanguineous parents. He started to sit at 8 months, stand at 20 months and walk at the age of 2; mental retardation, visual disturbance, cerebellar ataxia, myoclonus and epilepsy developed by the age of 10, and he died at 13. Neuropathological investigation revealed neuronal loss and storage. Severe loss of neurons was observed in the thalamus, globus pallidus, lateral geniculate body, gracile nucleus, Purkinje and retinal ganglion cells. Marked ballooning was seen in the Betz cells and neurons in the basal forebrain, the motor neurons in the cranial nerve nuclei and spinal cord, and in the trigeminal and spinal ganglia. The storage material varied in staining from region to region and from neuron to neuron. Electron microscopic investigation revealed a variety of intracytoplasmic and intranuclear inclusions: membranous cytoplasmic bodies, parallel, wavy-lamellar or tortuous tubular structures, lipofuscin-like irregular-shaped pleomorphic bodies, and cytoplasmic vacuoles with fine granules and lamellar materials. The severity of the neuronal loss did not seem to correlate with the amount of the storage materials, but with the presence of tortuous tubular inclusion.
    Materialart: Digitale Medien
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 82 (1991), S. 402-407 
    ISSN: 1432-0533
    Schlagwort(e): Gangliocytoma ; Ultrastructure ; Catecholamines ; Hypertension ; Spinal cord
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary An 8-year-old boy developed severe systemic hypertension during resection of an intramedullary tumor. The histological, ultrastructural and immunocytochemical characteristics of the tumor are those of a gangliocytoma. Based on the demonstration of tyrosine hydroxylase in neuronal tumor cells, it is postulated that catecholamine secretion was responsible for the systemic hypertension.
    Materialart: Digitale Medien
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  • 16
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 81 (1991), S. 408-417 
    ISSN: 1432-0533
    Schlagwort(e): Werdnig-Hoffmann disease ; Immunocytochemistry ; Ultrastructure ; Cytoskeleton ; Ubiquitin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Neuronal alterations in two cases of Werdnig-Hoffmann disease (WH) were investigated immunocytochemically and ultrastructurally. Ballooned neurons (BNs) were found in anterior horn, Clarke's column, dorsal root ganglion and thalamus. Anti-phosphorylated neurofilament antibodies preferentially stained the peripheral perikarya and proximal neuronal processes of BNs, whereas anti-ubiquitin antibodies preferentially stained the central perikarya of BNs. Ultrastructurally, BNs showed degenerative changes ranging from a diffuse increase of neurofilaments to a centrally accentuated accumulation of mitochondria and vesicular or membranous profiles. Our studies suggest that ubiquitinated degradation products accumulate in the center of the BN's perikaryon and displace aberrantly phosphorylated neurofilaments to the periphery. BNs in WH probably reflect an intrinsic alteration in the metabolism of neurofilaments that is associated with regressive changes in the neuron and eventually neuronal death.
    Materialart: Digitale Medien
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  • 17
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 82 (1991), S. 21-32 
    ISSN: 1432-0533
    Schlagwort(e): Muscle ; Regeneration ; Denervation ; Ultrastructure ; Snake toxin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary This study examines the level to which muscle regeneration proceeds in the absence of innervation. Regeneration was monitored in rat soleus muscles following localised injection of a snake toxin, notexin. Muscles which had been concomittantly denervated were compared with those that were normally innervated. Until 3–4 days following toxin administration regeneration is identical in both groups. The muscles contain new myotubes in place of the degenerated “parent” fibres. Thereafter, the non-denervated muscles grow rapidly and by 28 days their myofibres attain the size of those from the contralateral controls. Growth of denervated regenerating muscles, however, is retarded and is superseded by a gradual atrophy. In such muscles we further identify ultrastructural abnormalities from 7 days post-injection. These a re loss of individual myosin filaments and the presence of immature and abnormal configurations of the transverse system and triads. We, thus, conclude that innervation is an obligatory requirement for the restoration of normal myofibrillar and sarcotubular morphology, as well as growth, but is not necessary for the neo-formation of myofibres.
    Materialart: Digitale Medien
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  • 18
    ISSN: 1432-0533
    Schlagwort(e): MPS I-S ; Skin biopsy ; Ultrastructure ; Bone marrow transplant
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary An 11-year-old girl with mucopolysaccharidosis I Scheie phenotype (MPS I-S) received a bone marrow transplant (BMT) from her heterozygous HLA-identical LMC-non-reactive mother. Multidisciplinary studies were carried out and results evaluated 21 months after transplantation. Herein we report the ultrastructural findings pre-and post-BMT in skin. Multidisciplinary studies are commonly used to evaluate the benefits of metabolic correction following BMT in some MPS and other inherited metabolic disorders, and changes in morphology have been described in liver and few other tissues. In this case, we elected skin, since connective tissue is universally involved in MPS and is safely and easily obtainable. Comparison of skin biopsy specimens taken before and after BMT showed a considerable change in dermal fibroblast morphology, with marked reduction in cell size and the number and size of abnormal lysosomes, thus indicating the clearance of storage. Our results demonstrate that dermal cells respond to enzyme replacement therapy in MPS I-S, with the clearance of glycosaminoglycan lysosomal accumulation in connective tissue fibroblasts, which had near-normal morphology 21 months after BMT. Therefore, the practice of skin biopsy after BMT in MPS and other metabolic disorders in which dermal cells are involved should be encouraged.
    Materialart: Digitale Medien
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  • 19
    ISSN: 1432-0533
    Schlagwort(e): Hyperplasia ; Pituitary ; Pathology ; Prolactin ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Prolactin cell adenoma is the most frequently found lesion in surgically removed pituitaries of patients with hyperprolactinemia. However, in several instances, instead of prolactin cell adenoma, other lesions are encountered by morphological investigation. We report here the morphological findings in a patient with hyperprolactinemia who underwent transsphenoidal pituitary surgery for suspected prolactin cell adenoma. A morphological diagnosis of tumor could not be confirmed and massive diffuse prolactin cell hyperplasia was identified. The aim of this publication is to describe the lesion by histology, immunocytochemistry, electron microscopy, and in situ hybridization and to call attention to primary prolactin cell hyperplasia which can mimic prolactin cell adenoma.
    Materialart: Digitale Medien
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  • 20
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 82 (1991), S. 420-424 
    ISSN: 1432-0533
    Schlagwort(e): Blastomycosis ; North American Blastomy-cosis ; Brain tumor ; Opportunistic infection ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Except for isolated case reports, blastomycosis has not been identified as a significant problem in immunosuppressed patients. We describe an unusual case with blastomycotic infection of a cerebral glioma in a 56-year-old man who underwent radiotherapy for his tumor and died of fulminant blastomycotic pneumonia. This is believed to be the first reported case of Blastomyces dermatitidis infection of a cerebral glioma. The light microscopic and ultrastructural features of B. dermatitidis, the giant forms of which were encountered in our patient, are described, and the role of immuno-suppression due to steroid therapy in the pathogenesis of this fulminant infection are reviewed.
    Materialart: Digitale Medien
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  • 21
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 81 (1991), S. 562-571 
    ISSN: 1432-0533
    Schlagwort(e): Scrapie ; Ultrastructure ; Vacuolation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Ultrastructural examination of the superior colliculi of mice intraocularly inoculated with the ME7 strain of scrapie showed vacuolation early in the course of infection. Brains were examined between 85–260 days after monocular inoculation with scrapie. The mean incubation period for the development of clinical disease was 302 days. Vacuolation was seen initially in the contralateral superior colliculus and subsequently in the ipsilateral colliculus. In coded trails light microscopical vacuolation was seen from 218 days but ultrastructural examination showed that sparse vacuoles were inconsistently present in either or both of the ipsilateral and contralateral colliculi from 85 days; frequent vacuoles were seen from 190 days. Scrapie-induced vacuoles were differentiated from vacuoles present in control tissue by the presence of loculation or by a limiting double membrane which showed protrusion or proliferation of the innermost lamella. Vacuolation was seen in neuronal perikarya, myelinated fibres, dendrites and axonal presynaptic terminals. Vacuoles of myelinated fibres were observed within myelin and possibly also in the inner tongue of oligodendroglial cytoplasm. Whorled membrane configurations were also seen. Tubulovesicular particles, 40 nm in diameter, were recognised in two scrapie-infected mice. It is suggested that some scrapie vacuoles arise as a result of incorporation of abnormal membrane into organelles, possibly mitochondria, in neuronal perikarya and neurites and probably also within oligodendroglial cytoplasm and myelin.
    Materialart: Digitale Medien
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  • 22
    ISSN: 1432-069X
    Schlagwort(e): Inflammatory linear epidermal naevus ; Keratinization ; DACM ; Involucrin ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Skin lesions of three patients with inflammatory linear verrucose epidermal naevus (ILVEN) were examined. Histologically, orthokeratosis and parakeratosis were alternately seen in the acanthotic epidermis. By N-(7-dimethylamino-4-methyl-3-coumarinyl)maleimide staining, the horny cells in the parakeratotic epidermis showed a cytoplasmic SH pattern and a weak membranous SS pattern. The orthokeratotic epidermis revealed an increased involucrin expression, whereas the parakeratotic epidermis showed almost no involucrin expression. Ultrastructurally, in the parakeratotic epidermis, the living keratinocytes had prominent Golgi apparatuses and vesicles in the cytoplasm. In the intercellular spaces in the upper spinous layer through to the lower horny layer, an electron dense, homogeneous substance was deposited. The cytoplasm of the horny cells was filled with keratin filaments and contained remnants of nucleus and cytoplasmic membrane structures, and some lipid droplets. The marginal band formation was incomplete. Most of these ultrastructural abnormalities were not found in the orthokeratotic epidermis. There are both similarities and differences in histopathogenesis of the parakeratotic epidermis between ILVEN and psoriasis. A unique finding was the lack of involucrin expression in the ILVEN parakeratotic epidermis.
    Materialart: Digitale Medien
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  • 23
    ISSN: 1432-069X
    Schlagwort(e): Rhino mouse skin ; All-trans retinoic acid ; CD271 ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The histological and ultrastructural effects following 3 weeks' topical treatment with two agents (all-trans retinoic acid and a new synthetic retinoid-like substance, CD271) were evaluated on the epidermis and the epithelial wall of the pseudocomedones in rhino mouse skin. The comedolytic effects of these drugs were similar, and consisted of a reduction of the utricular diameter, with normalization of follicular units. Morphological examinations revealed a hyperplastic response with an increase in the number of cell layers of both epidermis and follicular epithelium, and modifications in keratinocyte differentiation. Ultrastructural changes in the epidermis and epithelial wall were observed mainly in the granular and horny layers, with increased desquamation, and a decrease in the cohesiveness of corneocytes. During the first week of treatment, some cutaneous toxic effects were noticed, but they normalized within two weeks. On the other hand, a fine granular material persisted in the intercellular spaces. It is confirmed that the skin of the rhino mouse is a good model for the evaluation of the comedolytic effects of drugs. Moreover, it reveals the specific effects of retinoids on epidermal differentiation. We have demonstrated that topically applied CD271 induces modifications similar to those obtained with all-trans retinoic acid. It is thus concluded that CD271 is a potentially effective anti-acne agent.
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  • 24
    Digitale Medien
    Digitale Medien
    Springer
    Archives of dermatological research 283 (1991), S. 141-148 
    ISSN: 1432-069X
    Schlagwort(e): Sjögren ; Larsson syndrome ; Ichthyosis ; Ultrastructure ; Lamellar body ; Keratinization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The ichthyosiform skin and the uninvolved skin of a 5-year-old Japanese female with Sjögren — Larsson syndrome were examined by light and electron microscopy to elucidate the keratinization disorder. Light microscopically, the epidermis of the ichthyosiform skin showed acanthosis, papillomatosis and hyperkeratosis. The horny cells had a basket-weave appearance. The granular cell layer was slightly thickened. Slight round cell infiltration and vascular dilatation were seen in the upper dermis. The uninvolved skin was histologically normal. Electron microscopically, in both ichthyosiform and uninolved skin, abnormal lamellar or membranous inclusions were present in the cytoplasm of horny cells of the epidermis. These inclusions appeared to be derived from some of the lamellar bodies and/or abnormal membranous structures found in the cytoplasm of spinous and granular cells. Mitochondria in the epidermal basal cells were more numerous in the ichthyosiform skin than in the uninvolved skin. These findings indicate that, whether the skin is involved or not, the epidermis of the patient with this disorder may always have a structural abnormality, which may be genetically determined. Local environmental factors may play a role in inducing the acanthosis and papillomatosis of the epidermis.
    Materialart: Digitale Medien
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  • 25
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 199 (1991), S. 423-426 
    ISSN: 1432-041X
    Schlagwort(e): Oogenesis ; Accessory nuclei ; Developmental gradients ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary In the oocytes ofTenthredo olivacea, accessory nuclei (AN) are formed by budding from the nuclear envelope of the oocyte nucleus. Newly formed AN contain electron-dense material of nuclear origin and are surrounded by a double envelope devoid of pores. Such structures are subsequently transported to the peripheral ooplasm (periplasm), where they grow to reach a final diameter of 5 µm. In the envelopes of advanced AN nuclear pores arise. Through these pores “nuage” material is extruded into the surrounding periplasm. These findings are discussed with respect to a possible involvement of AN in the establishment of developmental gradients in hymenopteran oocytes.
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  • 26
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 200 (1991), S. 77-85 
    ISSN: 1432-041X
    Schlagwort(e): Lysosomes ; Ultrastructure ; Chloroquine ; Blastocyst ; Mouse
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Mouse morulae are known to undergo cavitation as soon as some external cells have entered the sixth cell cycle (Garbutt et al. 1987). Since the early cytological features of cavitation are still unclear, we undertook a careful ultrastructural analysis of late morulae-nascent blastocysts. In addition, since maturation of lysosomes might be involved in the first step of cavity formation, we focused our attention on these organelles by means of the cytochemical localization of trimetaphosphatase activity and by the study of the effects of chloroquine on precavitation embryos. Our results suggest that cavitation starts in a few external cells (presumably competent cells entering the sixth cell cycle), by the chloroquine-sensitive formation of degradative autophagic vacuoles engulfing lipid droplets and vacuoles containing osmiophilic material. These complex structures enlarge (as a result of lipid metabolism?) and so transform into intrablastomeric cavities which, by means of a membrane fusion process, very rapidly become extracellular cavities that coalesce. The abembryonic pole of the blastocyst is determined in this way. Moreover, we suggest that the juxtacoelic cytoplasmic processes covering the inner cell mass (ICM) cells, which are known to restrict the expression of their totipotency during early cavitation (Fleming et al. 1984), are the latest remnants of the walls of the growing intrablastomeric cavities.
    Materialart: Digitale Medien
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  • 27
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 86 (1991), S. 60-72 
    ISSN: 1432-1106
    Schlagwort(e): Trauma ; Neuron ; Sodium ; Chloride ; Ultrastructure ; Mouse
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary To determine the contributions of sodium and chloride to ultrastructural changes after mechanical injury, we amputated primary dendrites of cultured mouse spinal neurons in low calcium medium in which sodium chloride had been replaced with either choline chloride or sodium isethionate or sodium propionate. Uninjured cultured neurons were also exposed to the sodium ionophore, monensin. A third set of neurons was injured in medium in which all sodium and calcium chloride had been replaced with sucrose. Neurons injured in low-calcium, low-sodium medium exhibited few ultrastructural changes, except very near the lesion, where there was some dilation of mitochondria and cisternae of the smooth endoplasmic reticulum (SER). Mitochondria in other regions of the neurons developed an electron opaque matrix, and those nearer to the lesion converted to the condensed configuration, characterized by expanded intracristal spaces as well as a dense matrix. If sodium but not chloride was present in the medium, there was some dilation of the Golgi cisternae after injury, as well as some increased electron opacity of the mitochondria. Monensin treated neurons also exhibited dilation of the Golgi cisternae. Neurons injured in sucrose-substituted medium showed none of the changes associated with injury in normal culture medium. These results indicate that sodium influx through the lesion is involved in the dilation of the SER, which is seen even in low-calcium medium, and that a permeant anion, such as chloride, is also involved. This dilation of the SER may result from uptake of calcium released from mitochondria in response to elevated cytosolic sodium. Dilation of the Golgi cisternae appears to be a response only to elevated intracellular sodium. Condensation of the mitochondria after injury is thought to be due to increased demands for ATP synthesis and may involve a “futile cycling” of calcium across the mitochondrial membrane, involving sodium-mediated calcium release in response to elevated intracellular calcium.
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  • 28
    Digitale Medien
    Digitale Medien
    Springer
    Sexual plant reproduction 4 (1991), S. 28-35 
    ISSN: 1432-2145
    Schlagwort(e): Tapetal cells ; Brassica oleracea L ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The ultrastructure of the secretory, binucleate tapetum of Brassica oleracea in the micro spore mother cell (MMC) stage through to the mature pollen stage is reported. The tapetal cells differentiate as highly specialized cells whose development is involved in lipid accumulation in their final stage. They start breaking down just before anther dehiscence. Nuclei with dispersed chromatin, large nucleoli and many ribosomes in the cytoplasm characterize the tapetal cells. The wall-bearing tapetum phase ends at the tetrade stage. The dissolution of tapetal walls begins from the inner tangential wall oriented towards the loculus and proceeds gradually along the radial walls to the outer tangential one. The plasmodesmata transversing the radial walls between tapetal cells persist until the mature microspore, long after loss of the inner tangential wall. After wall dissolution, the tapetal protoplasts retain their integrity and position within the anther locule. The tapetal cell membrane is in direct contact with the exine of the microspores/pollen grains and forms tubular evaginations that increase its surface area and appear to be involved in the translocation of solutes from the tapetal cells to the microspores/ pollen grains. The tapetal cells exhibit a polarity expressed by spatial differentiation in the radial direction.
    Materialart: Digitale Medien
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  • 29
    Digitale Medien
    Digitale Medien
    Springer
    Sexual plant reproduction 4 (1991), S. 176-181 
    ISSN: 1432-2145
    Schlagwort(e): Pollen ; Brassica napus ; Mitoses ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Brassica napus pollen development during the formation of the generative cell and sperm cells is analysed with light and electron microscopy. The generative cell is formed as a small lenticular cell attached to the intine, as a result of the unequal first mitosis. After detaching itself from the intine, the generative cell becomes spherical, and its wall morphology changes. Simultaneously, the vegetative nucleus enlarges, becomes euchromatic and forms a large nucleolus. In addition, the cytoplasm of the vegetative cell develops a complex ultrastructure that is characterized by an extensive RER organized in stacks, numerous dictyosomes and Golgi vesicles and a large quantity of lipid bodies. Microbodies, which are present at the mature stage, are not yet formed. The generative cell undergoes an equal division which results in two spindle-shaped sperm cells. This cell division occurs through the concerted action of cell constriction and cell plate formation. The two sperm cells remain enveloped within one continuous vegetative plasma membrane. One sperm cell becomes anchored onto the vegetative nucleus by a long extension enclosed within a deep invagination of the vegetative nucleus. Plastid inheritance appears to be strictly maternal since the sperm cells do not contain plastids; plastids are excluded from the generative cell even in the first mitosis.
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  • 30
    Digitale Medien
    Digitale Medien
    Springer
    Sexual plant reproduction 4 (1991), S. 166-175 
    ISSN: 1432-2145
    Schlagwort(e): Helianthus annuus ; Ultrastructure ; Micropyle ; Pollen tube ; Synergid degeneration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Ultrastructural studies made on the micropyle of sunflower before and after pollination resulted in the following observations. (1) The micropyle is closed instead of a hole or canal. The inner epidermis of the integument on both sides of the micropyle is in close contact at the apex of the ovule. The boundary between the two sides consists of two layers of epidermal cuticle. (2) The micropyle contains a transmitting tissue. The micropyle is composed of an intercellular matrix produced by the epidermal cells of the integument. (3) The micropyle is asymmetrical, and is much wider on the side proximal to the funicle. On the funicle side the cells adjacent to the micropyle are similar to those of the transmitting tissue: they have large amounts of intercellular matrix and contain abundant dictyosomes, rough ER, and starch grains, and provide an appropriate environment for growth of the pollen tubes. The cells distal to the funicle are rich in rough ER and lipid bodies; they lack large intercellular spaces. (4) The micropyle is variable in the axial direction, i.e., it is much larger and more asymmetric at the level distal to the embryo sac than at a level close to the embryo sac. After pollination, one to four pollen tubes are seen in a micropyle. During their passage through the micropyle, most pollen tubes are restricted to the side proximal to the funicle. There is a greater tendency (81%) for the degenerate synergid to be located toward the funicle, i.e., at the same side as the pollen tube pathway. The data indicate a close relationship between micropyle organization, orientation of pollen tube growth, and synergid degeneration.
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  • 31
    Digitale Medien
    Digitale Medien
    Springer
    Sexual plant reproduction 4 (1991), S. 226-234 
    ISSN: 1432-2145
    Schlagwort(e): Male germ unit ; Sperm cells ; Isolation ; Pollen tubes ; Brassica napus ; Pollen-tube inner plasma membrane ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Sperm cells of pollen tubes grown both in vivo and in vitro form a male germ unit. Extensions from both sperm cells of each pollen tube are closely associated with the tube nucleus. A high yield (2.7 × 104. 20 mg−1 pollen grains germinated) of intact sperm cells was obtained following release by osmotic shock from pollen tubes grown in vitro. Structural integrity of isolated sperm was maintained by isolation at low temperature in an osmotically balanced medium. At 4° C many isolated sperm pairs were still enclosed within the pollentube inner plasma membrane. Sperm cells not enclosed within this membrane no longer remained connected as a pair. During isolation vesicles formed on the sperm cell surface from disruption of the fibrillar components bridging the periplasmic space. Both in the pollen tube and after isolation the sperm nucleus is in close association with at least one region of the sperm plasma membrane. Sperm isolated at room temperature showed the presence of nucleopores, and nuclei were euchromatic, instead of heterochromatic as in intact sperm in the pollen tube.
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  • 32
    ISSN: 1432-2145
    Schlagwort(e): Cytoplasmic male sterility ; Beta vulgaris ; Microsporogenesis ; Tapetum ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The development of sporogenous and tapetal cells in the anthers of male-fertile and cytoplasmic male-sterile sugar beet (Beta vulgaris L.) plants was studied using light and transmission electron microscopy. In general, male-sterile anthers showed a much greater variability in developmental pattern than male-fertile anthers. The earliest deviation from normal anther development was observed to occur in sterile anthers at meiotic early prophase: there was a degeneration or irregular proliferation of the tapetal cells. Other early aberrant events were the occurrence of numerous small vesicles in the microspore mother cells (MMC) and a disorganized chromatin condensation. Deviations that occurred in sterile anthers at later developmental stages included: (1) less distinct inner structures in the mitochondria of both MMC and tapetal cells from middle prophase onwards. (2) dilated ER and nuclear membranes at MMC prophase, in some cases associated with the formation of protein bodies. (3) breakdown of cell walls in MMCs and tapetal cells at late meiotic prophase. (4) no massive increase in tapetal ER at the tetrad stage. (5) a general dissolution of membranes, first in the MMC, then in the tapetum. (6) abortion of microspores and the occurrence of a plasmodial tapetum in anthers reaching the microspore stage. (7) no distinct degeneration of tapetal cells after microspore formation. Thus, it seems that the factors that lead to abortive microsporogenesis are structurally expressed at widely different times during anther development. Aberrant patterns are not restricted to the tetrad stage but occur at early prophase.
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  • 33
    ISSN: 1432-2285
    Schlagwort(e): Air pollutants ; Chloroplasts ; Fluoride ; Olive tree leaves ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Leaves of olive trees growing in the vicinity of the Aluminium Factory of Greece were ultrastructurally investigated in order to determine any malformations caused by environmental air pollutants, especially hydrogen fluoride, in comparison with control samples and normal seasonal senescence. Estimation of some elements accumulated by these leaves showed that they contained high amounts of F and Al attributable to the operation of the nearby factory. The most seriously effected cell components were found to be the mesophyll chloroplasts that show a dilation of the intrathylakoid space, increase of the number of plastoglobuli, discoloration of plastoglobuli, accumulation of large starch grains and an overall disorganized appearance of the organelle. The nuclear crystalloid inclusions have unusual shapes, while the vacuoles contain a fibrillar/granular material that increases their electron density. It is concluded that the ultrastructural malformations are caused by a combination of environmental stresses and air pollutants.
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  • 34
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 264 (1991), S. 23-32 
    ISSN: 1432-0878
    Schlagwort(e): Male urethra ; Urethral epithelium ; Immunocytochemistry ; Ultrastructure ; Man
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The distal segment of the human male urethra, in particular the fossa navicularis, was studied with light- and electron microscopy as well as by means of histochemical and immunocytochemical methods. The fossa navicularis of the urethra contains a circumscribed zone of extremely thick, non-keratinized stratified squamous epithelium composed of cells containing a large amount of glycogen. These cells lack acid phosphatase activity and lysozyme-like immunoreactivity, both of which can be demonstrated to varying extents in the other zones of the distal male urethra. These glycogen-rich cells are considered to be the substrate for an endogenous flora of lactobacteria, whereas the acid-phosphatase activity and the lysozyme-like immunoreactivity indicate the presence of macrophages and the secretion of bactericidal agents at the epithelial surface. These observations suggest that the different zones with heterogeneous properties in the distal male urethra probably represent a defense system against the invasion of pathogenic microorganisms. Moreover, the glycogen-rich zone, which resembles the glycogen-rich epithelium of the vagina, is estrogen-dependent. This is demonstrated in cases of sex reversal in which after long-lasting estrogen treatment the glycogen-rich zone becomes extremely extended by displacement of the neighbouring epithelium.
    Materialart: Digitale Medien
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  • 35
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 263 (1991), S. 529-534 
    ISSN: 1432-0878
    Schlagwort(e): Melatonin ; Pituitary gland, pars tuberalis ; Secretory cells ; Cyclic AMP ; Ultrastructure ; Cell culture ; Sheep
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Functional receptors for melatonin have been localized and characterized on the pars tuberalis (PT) of a number of mammalian species, but the cell-type responsive to melatonin is unknown. The ultrastructure of the ovine pars tuberalis has been examined and these findings correlated with the functional response of the gland to melatonin. This study revealed that two secretory cell types predominate in the ovine PT, which differ in the abundance of dense-core granules. The most abundant of the cells are either agranular or very sparsely granulated and represent 90% of the total population, with the remaining 10% being composed of cells with abundant dense-core vesicles. Few follicular cells were observed. This ratio of secretory cell-types persisted in primary culture, with the two types non-separable by Percoll gradient centrifugation. Using forskolin, as a non-specific stimulant of adenylate cyclase, melatonin was shown to inhibit the formation of cyclic AMP by 80–90% in cells both before and after Percoll centrifugation. The results demonstrate that the agranular secretory cells of the ovine pars tuberalis are the melatonin responsive cell-type of this gland.
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  • 36
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 263 (1991), S. 567-572 
    ISSN: 1432-0878
    Schlagwort(e): Somatostatin ; Coeliac ganglion ; Autonomic innervation ; Ultrastructure ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Somatostatin-like immunoreactivity was localized in nerve cell bodies and nerve terminals in the cat coeliac ganglion. Two types of somatostatin-immunoreactive cell bodies were revealed, the first being large (diameter 35 μm), numerous and weakly labelled, where—as the second was considerably smaller (diameter 10.4 μm), sparsely distributed and heavily stained. The immunoreactive nerve terminals were in synaptic contact with many immunonegative large neurons and dendrites. However, in a few cases, somatostatin-immunoreactive nerve terminals could also be observed on the surface of lightly stained neurons. Transection of vagal or mesenteric nerve failed to affect the distribution or density of somatostatin-like immunoreactive nerve terminals. These results demonstrate the existence of a synaptic input to the principal neurons of the coeliac ganglion of the cat by somatostatin-containing nerve terminals and suggest that this peptide may act as a neuromodulator or neurotransmitter. It is proposed that somatostatin-positive neurons provide intrinsic projections to other somatostatin-positive and to somatostatin-negative neurons throughout the coeliac ganglion, thereby creating a complex interneuronal system.
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  • 37
    ISSN: 1432-0878
    Schlagwort(e): Preadipocytes ; Adipocyte precursor cells ; Adipose tissue ; Differentiation-cell cultures ; Ultrastructure ; Rat (Fischer 344)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Cultures of adherent mature adipocytes, obtained from collagenase-digests of adipose tissue of the rat, invaribly contain rapidly proliferating, fibroblastlike cells despite the washing and centrifugation procedures empolyed during isolation of the fat cells. Such spindle-like cells originate from low-density structures, which we term “islets”, that are present, together with the mature adipocytes, in the floating layer of the digest of adipose tissue. Islets are found in preparations from adult (3–4 months old) as well as aging (17–24 months old) rats. By light-and electron microscopy, the islets appear as clusters of closely associated cells containing a variable amount of lipid-like material. Cells of endothelial or pericytic origin are also present in the islets. Within a few hours of culture, the islets give rise to those spindle-like cells that have been seen to proliferate in the cultures. By 36–48 hours, such cells begin to accumulate lipid droplets and, by 150 hours, assume the morphology of small mature adipocytes (diameter 20–35 μm) with a large central lipid droplet. The pattern of differentiation of these cells recalls that of preadipocytes derived from the stromal-vascular fraction of adipose tissue digests. Nonetheless, the extent and rapidity of their adipose conversion, as well as the culture conditions necessary for differentiation, are different and suggest that these cells are a substantially uniform subpopulation of adipocyte-precursor cells highly committed to differentiation.
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  • 38
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 265 (1991), S. 193-196 
    ISSN: 1432-0878
    Schlagwort(e): Postnatal development ; Olfactory epithelium ; Supporting cells ; Receptor cell dendrites ; Ultrastructure ; Rat (Wistar)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The present electron-microscopical study reports ultrastructural changes occurring in the supranuclear region of the supporting cells of the rat olfactory epithelium during the first 16 days of postnatal life. These changes are concerned with the enclosure of receptor cell dendrites and an increase in the amount of smooth endoplasmic reticulum, which has a specific distribution in the supporting cell. An increase in microvillous projections at the free cell surface is also observed. Moreover, this report demonstrates that the cytoarchitecture of the apical portion of the olfactory epithelium at the 16th day of postnatal life is similar, with respect to the relationship between supporting cells and receptor cell dendrites, to that of adult animals.
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  • 39
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 266 (1991), S. 37-49 
    ISSN: 1432-0878
    Schlagwort(e): Microvessel endothelial cells ; Cell culture ; Corpus luteum ; Ultrastructure ; Cow
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Five different types of cultured microvessel endothelial cells defined by use of light microscopy and scanning electron microscopy in a preceding study were investigated by transmission electron microscopy. Type-1 cells displayed a deep invagination of the cell membrane or a single cilium. Granules of low electron density were abundant. A perinuclear ring of intermediate filaments occurred. Cultures of type-2 cells were subdivided into phenotype A, reminiscent of cell-type 1, and into phenotype B, assumed to be vascular smooth muscle cells. Many highly electron-dense granules appeared in late postconfluent cultures of both phenotypes. Cell-type 3 was conspicuous because of a large intracytoplasmic vacuole. Lysosomes with curvilinear bodies were found in cell-types 3 and 4. Both cell types developed a peripheral regular network of microfilaments. Cell-type 5 showed vesiculation of the rough endoplasmic reticulum, lipid droplets and a peripheral felt-like belt of microfilaments. Tubular forms seen in late postconfluent cultures of cell-types 1 to 3 displayed a core of extracellular matrix. Pseudotubular forms of cell-type 4 contained apoptotic bodies. Thus, as seen at the ultrastructural level, different features are maintained by cultured microvessel endothelial cells, suggesting that they have different inherent properties.
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  • 40
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 264 (1991), S. 369-375 
    ISSN: 1432-0878
    Schlagwort(e): Thymus ; CD4- ; CD8- ; thymocyte ; Thymic hematopoietic precursors ; Cytokines ; Ultrastructure ; Mouse (DBA/2, H-2d)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary We have previously shown that the interaction of thymocytes with thymic accessory cells (macrophages and/or interdigitating cells) is one of the factors required for thymocyte activation. Precursors of both thymic accessory cell and thymocytes are included in the CD4- CD8- Mac-1- Ia- subpopulation, and their respective maturation and/or activation may be modulated by granulocyte-macrophage colony-stimulating factor, interleukin 1 and interleukin 2. When CD4- CD8- thymic cells are activated with granulocyte-macrophage colony-stimulating factor plus interleukin 2, both macrophages and interdigitating-like cells are present, as shown by electron microscopy. When activated with interleukin 1 plus interleukin 2, the interdigitating-like cells is the only accessory cell present. In both culture conditions, large clusters are formed between interdigitating cells and lymphoid cells. These results have led us to propose two-step signals for thymocyte proliferation: first, the maturation of macrophages under granulocyte-macrophage colony-stimulating factor control and the production of interleukin 1, and secondly, the maturation of interdigitating cells under interleukin 1 control, their clustering with thymocytes which are then activated.
    Materialart: Digitale Medien
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  • 41
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 263 (1991), S. 597-600 
    ISSN: 1432-0878
    Schlagwort(e): Lamellate cell ; Ultrastructure ; Ciliary photoreceptors ; Nervous system, prochordates ; Branchiostoma lanceolatum (Acrania)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The lamellate cells of amphioxus have round nuclei, and cytoplasm with many mitochondria and a large amount of glycogen. Each of these cells projects a highly modified, branched cilium into the central canal, where it characteristically forms lamellar structures. Primary branches and secondary lamellae often contain accessory microtubules that are not derived from the axonema. The functional and evolutionary significance of this cell type is discussed in relation to the ciliary photoreceptors found in other chordates.
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  • 42
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 264 (1991), S. 161-165 
    ISSN: 1432-0878
    Schlagwort(e): Adenohypophysis ; Pars tuberalis ; Ultrastructure ; Immunohistochemistry ; Fetal ; Human
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The pars tuberalis of the adenohypophysis was investigated in three human fetuses at mid-gestation by electron microscopy or immunohistochemistry. In addition to gonadotrophs and thyrotrophs, identified by immunohistochemistry and ultrastructural morphology, electron microscopy revealed the existence of an additional differentiated cell type closely resembling “pars tuberalis-specific” cells known from other species. The role of this cell type in the human endocrine regulation remains to be elucidated.
    Materialart: Digitale Medien
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  • 43
    Digitale Medien
    Digitale Medien
    Springer
    Protoplasma 161 (1991), S. 23-30 
    ISSN: 1615-6102
    Schlagwort(e): 1,10-Phenanthroline ; Photodynamic herbicides ; Pisum sativum ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary We have examined ultrastructural changes of mesophyll cells in pea leaves induced by the photodynamic herbicide 1,10-phenanthroline (Phe). Dark incubation of pea plants did not cause any damage in plants or changes in the ultrastructure of mesophyll cells. Two hours of illumination after pretreatment with Phe caused photooxidative damage in plant but was not sufficient to markedly change the ultrastructure, although dilation of endoplasmic reticulum (ER) cisternae occurred. Illumination for 12 h caused inhibition of grana formation in pretreated plants. These ultrastructural changes and the inhibition of chlorophyll (Chl) accumulation may be due to the inhibition of transport of certain proteins to the plastids, diminished accumulation of chlorophyll proteins (e.g., LHCP) and a decrease in activity of the chlorophyll synthetase.
    Materialart: Digitale Medien
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  • 44
    Digitale Medien
    Digitale Medien
    Springer
    Protoplasma 161 (1991), S. 150-159 
    ISSN: 1615-6102
    Schlagwort(e): Abutilon ; Lucifer Yellow ; Microinjection ; Nectary ; Transport ; Trichome ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Intercellular transport was examined in nectary hairs ofAbutilon slriatum var.thompsonii using dye-uptake and microinjection followed by fluorescence and electron microscopy. Dye-uptake experiments demonstrated that both Lucifer Yellow CH (LYCH) and diaminobenzidine (DAB) move centrifugally along an apoplastic pathway from the sepellary tissue towards the tip cell. Further, fluorescence of LYCH could also be detected inside the cells of the nectary trichome. When LYCH or LYCH/DAB were microinjected into the tip cell, the dye spread in a centripetal direction towards the stalk cell. Electron microscopical investigations of microinjected nectary hairs revealed numerous electron-opaque globules in the cytoplasm of the nectary hair cells. In addition, multivesicular bodies, nuclei with opaque regions and changes in the rough endoplasmic reticulum (RER) were seen in nectary hair cells even at very low concentrations of injected dye. Ultrastructural investigations provided evidence for cytological changes in microinjected nectary hairs.
    Materialart: Digitale Medien
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  • 45
    Digitale Medien
    Digitale Medien
    Springer
    Protoplasma 163 (1991), S. 136-144 
    ISSN: 1615-6102
    Schlagwort(e): Corythion dubium ; Silica deposition ; Testate amoeba ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The siliceous body plates ofCorythion dubium are bound by a band of organic cement which is thickest at the lateral margins. The anterior vacuolar cytoplasm is separated by a pigment zone, which forms a dark band in the mid-body region, from the compact posterior region containing a typical vesicular nucleus surrounded by a region of dense endoplasmic reticulum. A pellicular basket of microtubules surrounds the posterior cytoplasm. The large Golgi complex lies between the nucleus and the fundus. Numerous coated and uncoated vesicles from the Golgi cisternae are seen in the peripheral cytoplasm alongside developing plates. These small siliceous plates are enclosed in silicon deposition vesicles lying in surface ruffles of the plasmalemma, often in association with a pair of microtubules. Observations are made on the formation of these vesicles and the early stages of silica deposition. A comparison is drawn between silica deposition inC. dubium and choanoflagellates where there is a similar association between silicon deposition vesicles and microtubules.
    Materialart: Digitale Medien
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  • 46
    Digitale Medien
    Digitale Medien
    Springer
    Protoplasma 163 (1991), S. 125-135 
    ISSN: 1615-6102
    Schlagwort(e): Cowpea ; Heat shock ; Thermoadaptation ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Suspension culture cells of cowpea (Vigna unguiculata) were examined using transmission electron microscopy to characterize morphological changes associated with hyperthermal stress. Cultures maintained at 26°C (unadapted cells) and 38°C (thermoadapted cells) were examined before and after exposure to elevated temperatures of 34°C and 45°C, respectively. Observations indicate that while there were significant ultrastructural differences between unadapted and thermoadapted cells, the following structural modifications in response to heat stress were observed in cells of both cultures: (a) almost a complete loss of polyribosomes, rough ER, and dictyosomes, (b) migration of intracellular waste material (presumably proteinaceous in composition) into the cell vacuole, (c) swelling of the nucleolus with assumed accumulation of preribosomal RNP granules, and (d) retraction of the tonoplast from the cytoplasm into the vacuoles of some cells. Heat shock granules (two size classes) were observed in the cytoplasm of stressed thermoadapted cells along with hollow-cored granules within the leucoplasts. Apart from a few minor differences, the morphological modifications that were made in apparent response to hyperthermal stress were remarkably similar in both cultures.
    Materialart: Digitale Medien
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  • 47
    ISSN: 1615-6102
    Schlagwort(e): Rhizobium meliloti ; Development ; Symbiosis ; Nitrogen fixation ; Ultrastructure ; Spontaneous nodule
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The development of spontaneous nodules, formed in the absence ofRhizobium and combined nitrogen, on alfalfa (Medicago sativa L. cv. Vernal) was investigated at the light and electron microscopic level and compared to that ofRhizobium-induced normal nodules. Spontaneous nodules were initiated from cortical cell divisions in the inner cortex next to the endodermis, i.e., the site of normal nodule development. These nodules, on uninoculated roots, were white multilobed structures, histologically composed of nodule meristems, cortex, endodermis, central zone and vascular strands. Nodules were devoid of intercellular or intracellular bacteria confirming microbiological tests. Early development of spontaneous nodules was initiated by series of anticlinal followed by periclinal divisions of dedifferentiated cells in the inner cortex of the root. These cells formed the nodular meristem from which the nodule developed. The cells in the nodule meristems divided unequally and differentiated into two distinct cell types, one larger type being filled with numerous membrane-bound starch grains, and the other smaller type with very few starch grains. There were no infection threads or bacteria in the spontaneous nodules at any stage of development. This size differentiation is suggestive of the different cell sizes seen inRhizobium-induced nodules, where the larger cell type harbours the invading bacteria and the smaller type is essential in supportive metabolic roles. The ontogenic studies further support the claim that these structures are nodules rather than aberrant lateral roots, and that plant possess all the genetic information needed to develop a nodule with distinct cell types. Our results suggest that bacteria and therefore theirnod genes are not necessarily involved in the ontogeny and morphogenesis of spontaneous and normal nodules in alfalfa.
    Materialart: Digitale Medien
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  • 48
    Digitale Medien
    Digitale Medien
    Springer
    European archives of oto-rhino-laryngology and head & neck 248 (1991), S. 144-146 
    ISSN: 1434-4726
    Schlagwort(e): Cricopharyngeus muscle ; Golgi tendon organ ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary An encapsulated nerve structure resembling the Golgi tendon organ was found in a human cricopharyngeus muscle near the cricoid cartilage where muscle fibers terminate. The capsule consisted of lamellated flattened cells with a basal lamina. Capsular cells separated the lumen into small compartments which contained myelinated and/or nonmyelinated nerve fibers. Nonmyelinated nerve fibers were also found in the interlamellar spaces of the capsular cells. Some nonmyelinated nerve fibers were dilated and contained abundant mitochondria, being partly surrounded by a Schwann cell sheath and embedded in collagen bundles. These features indicate that the nerve structure is a mechanoreceptor similar to the Golgi tendon organ. Its location and structure indicate that it is placed to detect the tension of the cricopharyngeus muscle.
    Materialart: Digitale Medien
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  • 49
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 28 (1991), S. 79-84 
    ISSN: 1040-452X
    Schlagwort(e): Yeast ; Ultrastructure ; Oocyte infection ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Notizen: Pathogenic yeast, Candida albicans, were incubated with hamster and human oocytes for up to 21 hours in order to determine the nature and time course of phagocytosis of these organisms. Aliquotes of the interacting cells were taken at various time intervals for electron microscopic examination. Some specimens had their zona pellucidae enzymatically removed prior to incubation with yeast, and these specimens showed the most extensive interaction and phagocytosis of Candida. The zona pellucida appears to be an effective barrier to yeast, at least over the time span studied. The observations are consistent with the hypothesis of an initial attachment of yeast via a surface component to oocyte microvilli followed by phagocytic uptake into an endosome. There is no compelling evidence of lysosomal degradation of the yeast over the time course of this study; however, the oocytes appear to undergo some degenerative changes at long incubation times.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 50
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 28 (1991), S. 189-198 
    ISSN: 1040-452X
    Schlagwort(e): Vitelline coat lysis ; Lysins ; Ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Notizen: Two proteins of molecular weights 20,000 (20K) and 15,500 (15.5K) are the major soluble substances released from the acrosomal vesicle of the abalone, Haliotis discus, spermatozoon. A crude preparation of them has been shown to possess lytic activity on the oocyte vitelline coat (VC). To elucidate the role(s) of each acrosomal protein (AP) in VC lysis, oocytes were examined after treatment with various AP preparations. The VC, which is about 1 μm thick, is composed of thin outer and inner electron-dense layers and a thick main layer of a fine filamentous feltwork. When oocytes were treated with a crude preparation containing both APs, the outer layer disappeared and the feltwork of the main layer loosened extensively. A preparation containing predominantly the 20K AP dissolved the outer layer completely and the main layer to some extent, whereas another preparation containing predominantly the 15.5K AP caused loosening of the main layer without alteration of the outer layer, suggesting that the 20K AP acts on the outer layer, whereas the 15.5K AP acts on the main layer. However, when purified, each AP by itself failed to dissolve the VC, although lysis occurred in a 1:1 mixture of these preparations. Moreover, when the oocytes were pretreated with the 20K AP and thoroughly washed, the 15.5K AP alone could induce lysis. These results suggest that the lysis of the outer layer requires both APs but not simulataneously. The 15.5K AP, which is located posteriorly in the acrosomal vesicle, must be released to act on the VC following the action of the 20K AP.
    Zusätzliches Material: 20 Ill.
    Materialart: Digitale Medien
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  • 51
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 29 (1991), S. 289-293 
    ISSN: 1040-452X
    Schlagwort(e): Postacrosomal region ; Cytoskeleton ; Ultrastructure ; Immunocytochemistry ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Notizen: Monoclonal antibody MN13 raised against mouse spermatozoa specifically recognizes the postacrosomal region of the sperm head in several mammalian species. Colloidal gold-immunoelectron microscopy of demembranated mouse spermatozoa indicated that the antigen is associated with the outer layer of the periodic substructure apparently linking the postacrosomal sheath to the overlying plasma membrane. The antigen recognized by MN13 may cotribute to the intimate association of the postacrosomal sheath with the overlying plasma membrane.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 52
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 30 (1991), S. 275-282 
    ISSN: 1040-452X
    Schlagwort(e): Human testis ; Cell separation ; Elutriation ; Spermatid ; Ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Notizen: Studying biochemical events in human spermatogenesis requires separated populations of spermatogenic cells. Dissociation of these cells was performed by a Trypsin-DNAse method adapted from the technique used for rodents. Cell separation was performed by centrifugal elutriation. Seven populations were collected, one further purified by Percoll gradient centrifugation, giving nine different cell populations. The efficiency of the cell separation was evaluated by phase contrast microscopy, flow cytometric DNA analysis, and electron microscopy. Five populations were enriched in spermatids: two in round spermatids (87% and 73%), another in round (52%) and elongating (44%) spermatids, another constituted by 80% elongating spermatids, and the last by 90% elongated spermatids. Two of the four remaining populations were enrichied in primary spermatocytes (74% and 54%); another population was the upper part of the Percoll gradient and constituted cytoplasmic lobes and residual bodies (89%); the last population was made up of various cells, with no specific enrichment. Electron microscopic observations revealed good preservation of the separated cells; only the flagella from elongated spermatids were lost. Furthermore, an unusual pattern of nucleoplasm distribution during stages 2-4 of spermatid differentiation was observed and its signification is discussed with regard to the shape of the human spermatozoon.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 53
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 18 (1991), S. 74-81 
    ISSN: 0741-0581
    Schlagwort(e): Confocal scanning laser microscopy ; Connective tissue ; Elastic tissue ; Eye ; Microvasculature ; Ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: The connections between elastic tissue and microvessels (arterioles, capillaries, and venules) in the rabbit eye were examined by light and electron microscopy. In particular, confocal scanning laser microscopy of tissue stained with orcein and examined by fluorescence using a rhodamine filter was correlated with electron microscopic observations. The goal was an analysis of the way in which elastic tissue of the uvea (i.e., choroid, ciliary body, and iris) and the optic nerve of the eye connect to the microvessels in these structures. Confocal microscopy revealed these connections advantageously and showed how they link the elastic tissue meshwork in the perivascular tissue spaces with the wall of the blood vessels. Electron microscopy showed that the connections consist of bundles of 10-12 nm diameter microfilaments that insert into vascular basement membranes. These connections may contribute to the vascular response to changes in blood pressure or intraocular pressure in the eye.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 54
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 19 (1991), S. 172-188 
    ISSN: 0741-0581
    Schlagwort(e): Testis ; Morphogenesis ; Cytodifferentiation ; Ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: The fetal testis is not merely a precursor of the adult organ: it is indeed an endocrine gland whose function is the masculinization of the fetus. It differs physiologically and morphologically from the adult testis. In this paper, the first stages of testicular differentiation in the rat are described, with special emphasis on the ultrastructural aspects. At the stage of 13.5 days after fertilization, the first Sertoli cells differentiate; they are characterized by a voluminous and little electron dense cytoplasm, a well-developed RER formed by vesicles and short cisternae filled with a flocculent material. Progressively, they polarize and adhere to one another by adherens-like junctions and cytoplasmic interdigitations to form the differentiating seminiferous cords. In the basal part of the Sertoli cells, a mat of microfilaments differentiates under the plasmalemma, while cytoplasmic blebs protruding in the extracellular space tend to disappear. A continuous basal lamina delineating the seminiferous cords begins to appear on day 14.5 and becomes widespread on day 15.5. These observations, when compared with other data from the literature, emphasize the fact that the differentiation of the Sertoli cells is the first morphological event during testicular differentiation. A possible role of the Sertoli cells in the subsequent organogenesis of the testis is suggested.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
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  • 55
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 17 (1991), S. 412-436 
    ISSN: 0741-0581
    Schlagwort(e): Human sperm ; Ultrastructure ; Pathology ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: In this article, the major contributions of electron microscopy to the present understanding of the physiology and pathophysiology of the human spermatozoon are reviewed. The ultrastructural organization of sperm organelles playing a significant role for cell function and, therefore, for the reproductive process is described. Also, the major abnormalities and defects of the various organellar systems and how they impair the reproductive function and/or the viability of the cell are reviewed.
    Zusätzliches Material: 43 Ill.
    Materialart: Digitale Medien
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  • 56
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 19 (1991), S. 276-290 
    ISSN: 0741-0581
    Schlagwort(e): Cryofixation ; Endothelium ; Blood Vessels ; Ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: Cryofixation refers to the immobilization of tissue components by the rapid removal of heat from the specimen, so that the structure is interred and stabilized in a natural embedding medium, namely, frozen (amorphous or microcrystalline) tissue water. Cryofixation is now often used as a complement to the more traditional fixation methods, especially when the cell structure is delicate or dynamic and may be inaccurately preserved by the slow selective action of chemical fixatives. Vascular endothelial cells are specialized for transcellular transport and for the regulation of blood flow and composition. The dynamic and labile subcellular organization of these cells, presumably reflecting these functional specializations, makes them ideal candidates for cryofixation.Several different types of endothelial cells were directly frozen at temperatures below 20 degrees Kelvin by pressing them against a liquid-helium-cooled block. These samples were subsequently processed for structural analysis by freeze-substitution. Detailed rationales, designs, and protocols are described for both freezing and freeze-substitution.Electron micrographs of cryofixed arterial and venous capillaries (rete mirabile of the American eel), iliac vein (rabbit), and cultured endothelium from the iliac vein (human) reveal that the organization of the characteristic intracellular membrane system of endothelial vesicles is qualitatively similar to that seen in chemically fixed endothelium, especially with regard to the interconnection of clusters of individual vesicles to form elaborate networks. The luminal and abluminal networks are not in communication, at least not in static images. Quantitatively, however, most directly frozen endothelial cells have far fewer vesicular profiles than comparable glutaraldehydefixed cells. The differences can be explained by presuming that the rapid action of cryofixation (approximately 1 msec) gives a more accurate picture of the vesicular network because it captures the transient structure of labile or dynamic membranes.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
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  • 57
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 19 (1991), S. 107-117 
    ISSN: 0741-0581
    Schlagwort(e): Plant ; Leaf ; Root ; Tissue ; Ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: Cryofixation and freeze substitution methods were developed for ultrastructural studies of cells in complex plant tissues. Leaf tissues and root tips of tobacco (Nicotiana tabacum L. var. Maryland Mammoth) were frozen with a RMC MF7200 propane jet freezer and freeze substituted sequentially with tannic acid and osmium tetroxide/uranyl acetate in acetone. High quality preservation was consistently obtained for epidermal and phloem cells of the leaf, and epidermal, cortical, meristematic, and cap cells of the root tip. Leaf mesophyll cells were also often well frozen. Organelles, including nuclei, endoplasmic reticulum, mitochondria, Golgi bodies, and plastids, showed excellent structural integrity and contrast. Most notable is the superior preservation of the cytoskeleton. Our results demonstrate that the propane jet freezer can be used routinely for high quality cryofixation of higher plant cells in certain complex tissues. This could have important implications for the use of cryofixation approach in a wide range of research in plant biology.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
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  • 58
    Digitale Medien
    Digitale Medien
    Springer
    Biology and fertility of soils 9 (1990), S. 101-109 
    ISSN: 1432-0789
    Schlagwort(e): Phryganella acropodia ; Testate amoeba ; Growth rate ; Rhizopoda ; Feeding ; Fungal species ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Clones of Phryganella acropodia were cultivated under different trophic conditions with bacteria as the food source. The doubling time was estimated to be 3 days. The edibility of four species of fungi, Aspergillus niger, Cunninghamella echinulata, Penicillium echinulatum and Stilbella bulbicola, was tested, but only Penicillium enchinulatum and Stilbella bulbicola were eaten and digested by the amoeba. An ultrastructure examination showed that there are two contractile vacuoles, many dictyosomes, a single nucleus with several nucleoli, and peroxisomes. The pseudopodia are filiform when attached to the substrate but change to lobose when the animal is floating. A thin organic membrane covers the aperture of resting forms.
    Materialart: Digitale Medien
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  • 59
    ISSN: 1432-2307
    Schlagwort(e): Gastric carcinoma ; Capillaries ; von Willebrand factor ; Ultrastructure ; Immuno-electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The microvasculature of the stroma of human gastric carcinoma was studied by immuno-electron microscopy for factor VIII/von Willebrand factor (vWF) and conventional electron microscopy. In differentiated type (intestinal) gastric carcinoma (9 cases), capillaries were distributed more densely around carcinoma cell nests. vWF was localized in endothelial cells and neighbouring stroma. Ultrastructurally, capillary endothelial cells showed considerable hypertrophic changes with well-developed rough endoplasmic reticulum (rER). vWF was localized in well-developed rER, granules, Weibel-Palade bodies (WPB), in the vascular lumen as clusters, and diffusely deposited in the subendothelium. This indicates that endothelial cells in this group are transformed into a state of active protein production. In undifferentiated type (diffuse) gastric carcinoma (12 cases), capillaries were uniformly distributed and endothelial hypertrophic changes were less remarkable. vWF was localized in WPB, scanty rER and subendothelial matrix. Solid capillary buds were observed in both types; they were composed of a solid strand of endothelial cells without a visible lumen. Our results reveal that the microvasculature in tumour stroma differs significantly according to its histological type.
    Materialart: Digitale Medien
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  • 60
    ISSN: 1432-2307
    Schlagwort(e): Mucus-granule-containing ciliated cell ; Ciliated metaplasia ; Transitional form ; Gastric mucosa ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Ciliated cells were found in the gastric mucosa in close association with intestinal metaplasia, mainly in the pyloric mucosa, of Japanese patients. The occurrence of ciliated cells is believed to be an acquired phenomenon and is considered to be a type of metaplasia; the term “ciliated metaplasia” is used to describe this phenomenon. Ciliated cells are found in the basal part of the glands among normal-looking mucous cells, mucous neck cells and neuroendocrine cells, but never on the surface or in foveolar epithelium. In ciliated cellcontaining glands, mitoses were noted in the neck region and the ultrastructural features of these cells were identical to those of undifferentiated neck cells. However, cell metaplasia from undifferentiated cells to metaplastic ciliated cells has never been demonstrated previously. The small mucus-granule-containing ciliated cells found in our present study may arise subsequent to division of undifferentiated neck cells into mucous cells with some daughter cells then exhibiting differentiation characteristics specific to ciliated cells. Thus they contain a mixture of both small mucus granules and numerous basal bodies and cilia, at the same time as a transitional form.
    Materialart: Digitale Medien
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  • 61
    ISSN: 1432-2307
    Schlagwort(e): Cardiomyopathies ; Ultrastructure ; Morphometry ; Mitochondria ; Myofibrils
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary We performed an ultrastructural, morphometric comparison of mitochondria and myofibrils of cardiomyocytes using endomyocardial biopsy specimens in hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM). Biopsies came from the right ventricular side of the interventricular septum in nine patients with HCM, nine with DCM, and nine controls with arrhythmia and/or ST depression. Morphometric analysis was carried out using electron microscopic photographs and an image analyser. Mitochondria were significantly greater in number and smaller in size in HCM than in the control group. In DCM, the size of mitochondria was also significantly smaller than in the control group, although their number was similar to that of the control group. No statistically significant difference was found regarding the size of mitochondria between HCM and DCM. The percentages of both mitochondrial and myofibrillar areas in cytoplasm were smaller in the DCM than the HCM and control groups, though no difference was seen between the latter two. The ratio of mitochondrial area to myofibrillar area was almost the same in each group. These results suggest increased mitochondrial function to match hypertrophic cardiomyocytes in HCM, and decreased mitochondrial function and cardiomyocytic contractility in DCM.
    Materialart: Digitale Medien
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  • 62
    Digitale Medien
    Digitale Medien
    Springer
    Virchows Archiv 417 (1990), S. 113-118 
    ISSN: 1432-2307
    Schlagwort(e): Minute chemodectoma ; Lung ; Ultrastructure ; Immunohistochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary So-called minute pulmonary chemodectoma is a curious, small lung tumour found mainly in women. The nature and origin of the proliferating cells are still obscure. In the first report on the tumour, the component cells were described as resembling chemoreceptor cells and the tumour was named chemodectoma. However, electron microscopic studies of the tumour have revealed no evidence of neuronal characteristics and have shown a close resemblance to meningothelial cells. In this study, the electron microscopic findings were similar to those previously reported but in one of the two cases, tumour cells were filled with abundant cytofilaments, giving them an occasional dense, patch-like appearance. Immunostaining for myosin and vimentin was positive in all tumour cells, but epithelial membrane antigen staining was not seen. These findings indicate that the tumour might have its origin from muscle cells.
    Materialart: Digitale Medien
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  • 63
    Digitale Medien
    Digitale Medien
    Springer
    Virchows Archiv 417 (1990), S. 395-404 
    ISSN: 1432-2307
    Schlagwort(e): Ultrastructure ; Non-Hodgkin's lymphoma ; Signet-ring cell ; Endoplasmic reticulum ; Multivesicular body
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary New ultrastructural findings are reported from two lymphomas of vacuolar signet-ring cell morphology (SR+), one of B cell and one of T cell lineage. When these lymphomas were compared ultrastructurally a difference in the relationship of the endoplasmic reticulum (ER) to the vacuole was noted, although the fine structure of the vacuoles themselves was similar and they were interpreted as giant multivesicular bodies (mvbs). Smooth ER was found near the vacuoles in both cases. Dark mvbs with a complex, reticulate form are emphasised as readily identified but hitherto unreported cell components in these tumours. A further B cell lymphoma of centroblastic/centrocytic type which was SR− was found to be rich in mvbs and may be a transitional form between SR− and SR+ lymphomas. In addition, the occurrence of mvbs has been studied quantitatively in a number of other lymphomas and in B and T lymphocytes in reactive nodes. Although increased numbers of mvbs were found in neoplastic compared with reactive lymphocytes, and in T compared with B cell lymphomas, these differences were not statistically significant. The possible roles of endoplasmic reticulum and mvbs in the generation of SR+ change are discussed.
    Materialart: Digitale Medien
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  • 64
    ISSN: 1432-2307
    Schlagwort(e): Purkinje fibres ; Transitional cells ; Working myocardium ; Global ischaemia ; Ultrastructure ; Contraction state
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Contraction bands usually occur in the intramural working myocardium following post-ischaemic reperfusion. In the subendocardium, however, they are found during ischaemia. Thus, we ascertained the contraction states of Purkinje fibres, transitional cells, subendocardial and intramural parts of the working myocardium during 30 min global ischaemia at 25° C. The effects with and without myocardial protection were compared. At the onset of pure ischaemia contraction bands are completely lacking in all cell types. During pure ischaemia contraction bands are found in all subendocardial cell types but not in the intramural working myocardium. A peak of pathological contraction states is found in the intramural working myocardium at the onset (0 min), in the subendocardial working myocardium at 10 min, in the transitional cells and Purkinje fibres at 30 min of pure ischaemia. Histidine-, tryptophan-, ketoglutarate-enriched (HTK) cardioplegia prevents contraction bands completely at the onset of ischaemia and prevents both contraction bands and pathological contraction states during ischaemia almost completely. Striking differences in the physiological contraction states are seen only in the working myocardium: HTK cardioplegia brings about dominance of relaxation during ischaemia. These findings may be due mainly to the effects of global ischaemia on the one hand and to catecholamines, calcium and oxygen on the other.
    Materialart: Digitale Medien
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  • 65
    Digitale Medien
    Digitale Medien
    Springer
    Virchows Archiv 417 (1990), S. 443-447 
    ISSN: 1432-2307
    Schlagwort(e): Mesothelioma ; Pathology ; Ultrastructure ; Peritoneum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Well-differentiated papillary mesothelioma (WDPM) is considered to be a distinct subtype of peritoneal mesothelioma. Although the WDPM is usually qualified as benign, the natural history of this lesion has not been clearly established. This report relates to two WDPMs which were found incidentally. In a 51-year-old man the WDPM developed over a period of 5 years into a typically malignant diffuse mesothelioma. Thus, although the WDPM morphologically lacks signs of malignancy, it should be regarded as a borderline mesothelioma.
    Materialart: Digitale Medien
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  • 66
    ISSN: 1432-0533
    Schlagwort(e): Olivopontocerbellar atrophy ; Argyrophilic inclusion ; Pontine nucleus ; Ubiquitin ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Patients with olivopontocerebellar atrophy (OPCA) were studied, and cytoplasmic inclusions were observed in some of the remaining neurons of the pontine nuclei, nuclei reticularis tegmenti pontis and arcuate nuclei. The cytoplasmic argyrophilic inclusions were demonstrated by silver impregnation techniques such as Bielschowsky and Bodian staining. With hematoxylin and eosin stain, the inclusions were sharply demarcated and appeared pale. The inclusions were not stained by the following routine histological methods: Klüver-Barrera, phosphotungstic acid hematoxylin, Holzer, periodic acid-Schiff, Mallory azan, alcian blue, nile blue, Masson trichrome, Congo red, thioflavine S, oil red O and Sudan black B stains. Immunohistochemistry with anti-ubiquitin antiserum showed that these inclusions were ubiquitinated. However, the inclusions did not react with any of the following antibodies (Abs) or antisera: anti-phosphorylated neurofilament (NF) Ab, anti-nonphosphorylated NF Abs (160 and 200 kDa), anti-paired helical filament antiserum, anti-tau antiserum, anti-tubulin Abs (alpha and beta), anti-microtubule-associated proteins antiserum, anti-glial fibrillary acidic protein antiserum, anti-vimentin Ab, anti-desmin Ab, anti-cytokeratin Abs (low and high molecular weights), anti-actin antiserum, anti-skeletal myosin antiserum and anti-myelin basic protein Ab. Ultrastructurally, the inclusion bodies noted in OPCA were composed primarily of fibrils having a width ranging from about 24 to 40 nm, which were entirely coated with osmiophilic granular material along their whole length. They were occasionally intermingled with a few filaments about 10 nm in width. Electron microscopical examination on silver-impregnated specimens revealed that each granule-coated fibril had a great affinity for silver particles. In elucidating the pathogenesis of OPCA, it was considered to be an important neuropathological finding that some of the remaining pontine neurons affected by OPCA developed characteristic cytoplasmic argyrophilic inclusions.
    Materialart: Digitale Medien
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  • 67
    ISSN: 1432-0568
    Schlagwort(e): Chloride cell ; Teleost ; Gills ; Ultrastructure ; Adaptation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The general gill morphology of Oreochromis alcalicus grahami, a teleost adapted to high salinity and hyperosmosis, is basically similar to that of other teleostean fish. The species has four pairs of gill arches, all of which have well developed filaments. Each of the arches (holobranchs) has two rows of filaments (hemibranchs). Bilaterally situated secondary lamellae branch from the central axis of the filaments. The lamellae reach their maximum size at the middle of the filament, gradually decrease in size and eventually disappear towards the tip of the filament, which is bare. The leading edge of the gill filament and the immediate interlamellar space is covered by a stratified epithelium consisting of pavement cells, mucous cells, chloride cells and undifferentiated cells. The surface of these cells is made up of concentric microridges. The chloride cells were found only on the primary epithelium (filamental epithelium) and very rarely on the secondary epithelium (lamellar epithelium). Two types of chloride cells were observed in the gills of Oreochromis. The superficial chloride cells have fewer mitochondria concentrated towards the basal aspect of the cell, and a network of tubules towards the apical surface and are less electron dense. These cells intercommunicate with the water through an apical pore. The deep chloride cells have numerous diffuse mitochondria intercalated between a fine profuse tubular network and are more electron dense. These cells are covered by one or more layers of pavement cells and thus do not have access to the external surface. After gradual dilution of the lake water in which the fish were kept, both types of chloride cells remained topographically and ultrastructurally distinct. However, in both kinds of cell the mitochondria decreased in number and size. Initially there was an increase in the diameter and the degree of interdigitation of the tubules followed by a gradual decrease. An increase in the quantity of rough endoplasmic reticulum, particularly at the perinuclear region of the cell, was noted. The morphometric analysis of the branchial system indicated that the gills of Oreochromis are well adapted for gas exchange by having numerous and relatively long gill filaments with a high lamellar density. These features provide a large surface for gas exchange which, when coupled with the notably thin water-blood barrier of an average thickness of only 0.83 μm, would facilitate efficient absorption of oxygen by the gills. Oreochromis alcalicus was observed to be incapable of adapting to freshwater. This may have been due to the progressive degeneration of the chloride cells. Also the arrangement of the chloride cells as a continuum from the central venous compartments to the free epithelial surface is a structural feature which may not be amenable to radical functional changes.
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  • 68
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 181 (1990), S. 195-213 
    ISSN: 1432-0568
    Schlagwort(e): Cell death ; Degeneration ; Embryo ; Development ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Physiological cell death is a widespread phenomenon in the development of both vertebrates and invertebrates. This review concentrates on an aspect of developmental cell death that has tended to be neglected, the manner in which the cells are dismantled. It is emphasized that the dying cells may adopt one of at least three different morphological types: “apoptotic”, “autophagic”, and “non-lysosomal vesiculate”. These probably reflect a corresponding multiplicity of intracellular events. In particular, the destruction of the cytoplasm in these three types appears to be achieved primarily by heterophagy, by autophagy and by non-lysosomal degradation, respectively. The various mechanisms underlying both nuclear and cytoplasmic destruction are reviewed in detail. The multiplicity of destructive mechanisms needs to be born in mind in studies of other aspects of cell death such as the signals which trigger it, since different signals probably trigger different types of cell death.
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  • 69
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 80 (1990), S. 118-122 
    ISSN: 1432-0533
    Schlagwort(e): Mitochondrial encephalomyopathy ; Extraocular muscle ; Ultrastructure ; Mitochondrial myopathy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary We carried out a histological examination of the extraocular muscles (EOMs) in a case of myoclonus epilepsy associated with ragged-red fibers (MERRF) and two cases of mitochondrial myopathy, encephalopathy, laetic acidosis, and stroke-like episodes (MELAS), which did not manifest external ophthalmoplegia clinically. By light microscopy, many granular and vesicular fibers were seen associated with endomysial fibrosis. Electron microscopy revealed that the fibers showed prominent accumulation of abnormal mitochondria, extensive loss of myofibrils, proliferation of free sarcoplasmic reticulum and an increased amount of lipid vacuoles. These changes were more pronounced in MELAS than in MERRF. Hirano bodies were often seen in the subsarcolemmal area of muscle fibers and also in the intramuscular myelinated nerve fibers and axon terminals. These findings suggest the presence of mitochondrial myopathy of the EOMs in cases of MELAS and MERRF.
    Materialart: Digitale Medien
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  • 70
    ISSN: 1432-0533
    Schlagwort(e): Cerebral ischemia ; Delayed neuronal death ; Gerbil ; Hippocampus ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Ultrastructural damage leading to delayed neuronal death was investigated in the mid-CA1 region of the hippocampus from the stratum (str.) moleculare to oriens after transient bilateral forebrain ischemia in Mongolian gerbils. After ischemia for 5 min without recirculation, mild swelling of the peripheral part of the apical and basal dendrites was already apparent in the str. moleculare and str. oriens. Mitochondria in the dendrites were also swollen in the same area. During recirculation for 12 h to 3 days, swelling of the dendritic cytoplasm persisted with formation of microvacuoles, but swelling of mitochondria receded. Microvacuolation and loss of microtubules were also observed in the proximal part of the dendrites during this period, and swelling and disruption of internal cristae were observed in mitochondria after recirculation for 3 days. The dendrites became severely degenerated after recirculation for 4 days. In the pyramidal cell bodies, no abnormality was observed at the end of ischemia for 5 min, but disaggregation of polyribosomes and swelling of the endoplasmic reticulum were observed 12 h after recirculation. Proliferation of the endoplasmic reticulum in parallel arrays occurred after recirculation for 1 day and persisted. Severe degeneration of the pyramidal cell bodies was obvious after recirculation for 4 days. The findings observed in the present investigation suggested that the neuronal structure most vulnerable to ischemia was the peripheral part of the dendrites and postischemic neuronal damage occurred early in this part of the dendrites.
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  • 71
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 80 (1990), S. 547-553 
    ISSN: 1432-0533
    Schlagwort(e): Feline ; Olfactory neuroblastoma ; Type C retrovirus ; Immunocytochemistry ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Three cases of spontaneous olfactory neuroblastoma (ONB) in domestic cats were morphologically and immunocytochemically characterized. Diagnostic light microscopic features included Flexner and Homer-Wright rosettes, while ultrastructurally the cells had neuritic processes, intracellular intermediate filaments, and intercellular junctions. Immunocytochemically, the tumors stained positively for neuron-specific enolase, cytokeratins, and S-100 protein antigens. In each case, a key finding was the identification of numerous mature type C retroviral particles within the tumors. In one case, budding of viral particles from the plasmalemma of tumor cells suggested the source of mature particles. This cat and one other were tested, and both were serologically positive for feline leukemia virus (FeLV). The virus in the tumors was identified as FeLV by polymerase chain reaction and immunocytochemistry. No other neoplasms were found in any of the cats, nor was there similar evidence of active viral infection in other non-tumor tissues, including the brain. Although the relationship between FeLV infection and ONB is uncertain, our findings indicate that FeLV should be investigated as an etiologic agent of ONB.
    Materialart: Digitale Medien
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  • 72
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 80 (1990), S. 611-617 
    ISSN: 1432-0533
    Schlagwort(e): Intranuclear inclusions ; Endoplasmic reticulum ; Hyaline inclusions ; Striated muscle ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Large intracytoplasmic inclusions arising from the endoplasmic reticulum and nuclear envelope were found in the muscle fibers of a 32-year-old individual with a life-long, chronic and progressive sensory-motor neuropathy. The morphological features of the inclusions were similar to that occasionally reported in the striated muscles in several unrelated conditions as well as to “hyaline” or “colloid” inclusions commonly seen in motor neurons of the brain stem and spinal cord. The chemical nature of the inclusions is not known. Their occurrence in the muscle fibers is probably secondary to chronic denervation.
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  • 73
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 80 (1990), S. 597-603 
    ISSN: 1432-0533
    Schlagwort(e): Choroid plexus ; Amyloid ; Intracellular inclusions ; Ultrastructure ; Immunocytochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Intracellular inclusions with staining properties of amyloid are very common in the aging choroid plexus epithelial cells. In many ways these inclusions show similarities with the neurofibrillary tangles, found in cerebral cortical neurons in patients with Alzheimer's dementia. We have now designed a purification method for choroid plexus amyloid and performed a transmission and scanning electron miscroscopic study. This shows that one form of choroid plexus inclusions, the Biondi ring, is a homogeneous globule covered with a thin layer of amyloid fibrils. Partial immunochemical characterization of the choroid plexus amyloid reveals that it is different from the neurofibrillary tangles although there are similarities.
    Materialart: Digitale Medien
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  • 74
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 182 (1990), S. 103-112 
    ISSN: 1432-0568
    Schlagwort(e): Fibroblast ; Myofibroblast ; Interstitial cell ; Vitamin A storing cell ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Scanning electron microscopic observations of connective tissue cells show a new aspect of the nature of fibroblasts, and the subsequent broad survey of references makes clear that fibroblasts of many tissues have various features which are regarded as atypical of fibroblasts, and at the same time that various connective tissue cells in different organs have features typical of fibroblasts. Both morphological and functional features of fibroblasts are more or less common to those of fibroblast-like cells, and differences among these cells are quantitative rather than qualitative. Therefore, it is almost impossible to set clear-cut criteria for distinguishing genuine fibroblasts from a large population of fibroblast-like cells. The majority of cells sharing features of fibroblasts, if not all, seem to belong to the same population of cells. They are probably adapted to special functional needs in their own micro-environment that are peculiar to local or pathological or experimental conditions. It is proposed to categorize these cells into subtypes depending on their main functions: 1, fibrogenesis; 2, tissue skeleton or barrier; 3, intercellular communication system; 4, gentle contractile machinery; 5, endocrine activity; and 6, vitamin A-storing. Re-evaluation of fibroblasts and fibroblast-like cells is required to facilitate their better understanding.
    Materialart: Digitale Medien
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  • 75
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 181 (1990), S. 325-331 
    ISSN: 1432-0568
    Schlagwort(e): Oocyte maturation ; Ultrastructure ; Fox ; Ovulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Blood samples were taken weekly from seventeen mature blue fox vixens (average age five years), from late anoestrus until pro-oestrus, and then taken daily. The vixens were sacrificed at various stages of oestrus, and oocytes were collected from ovarian follicles by aspiration, and/or from oviducts by flushing. The structural features of oocyte maturation were related to the time of the luteinizing hormone (LH) peak. On days 1–2 after the LH peak the oocyte nucleus migrated from a central to a peripheral position in the ooplasm and assumed a flattened appearance. The cumulus investment expanded simultaneously and ovulation took place around day 2. On days 2–3 the oocyte nuclear envelope broke down, the nucleoli disappeared, the metaphase of the first meiotic division was reached, the Golgi complexes decreased in size, the perivitelline space enlarged, and all junctional contact between cumulus cell projections and oocyte was disrupted. On days 3–5 the first polar body was extruded, the metaphase of the second meiotic division was reached, and the cumulus cells degenerated. On day 5 the release of cortical granule content was occasionally seen, and from day 6 the oocytes showed signs of degeneration. In a few animals deviant oocyte maturation was noticed.
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  • 76
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 181 (1990), S. 37-48 
    ISSN: 1432-0568
    Schlagwort(e): Axons ; Astrocytes ; Oligodendrocytes ; Ultrastructure ; Paedomorphosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In five species of lungless salamanders, family Plethodontidae, which all show highly developed visual abilities, the ultrastructure of the optic nerve was investigated and the total number of retinal ganglion cell axons, the percentage of myelinated axons, and the volume densities of glia and axons were determined. More than 80% of all axons were smaller than 0.4 μm and only 2–3% were larger than 0.8 μm. In individual nerves the degree of myelination varied between 1 and 9% which is in the range reported for other amphibian species. The miniaturized and highly paedomorphic species Batrachoseps attenuatus was an exception because only very few or even no myelinated axons were present in the nerve, which is unique among gnathostome vertebrates. The five investigated species had total numbers of axons ranging from 26000 in Batrachoseps attenuatus to about 50000 in Plethodon jordani. These numbers are the lowest found among vertebrates with an elaborated visual system. The amount of glial material in the optic nerve varied between 25 and 50%, with larger nerves possessing more glia than smaller ones. Ultrastructural analysis revealed that the optic nerve of each species contained both astrocytes and oligodendrocytes, although often in immature form. In Batrachoseps attenuatus the glia showed features of both astrocytes and oligodendrocytes which reflect an undifferentiated state.
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  • 77
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 181 (1990), S. 59-66 
    ISSN: 1432-0568
    Schlagwort(e): Ultrastructure ; Marmoset ; Chorionic villi
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The ultrastructural morphology of developing chorionic villi in the marmoset monkey (Callithrix jacchus) placenta was studied in pregnant monkeys at known time intervals after ovulation. In samples obtained at 45 days after ovulation the mesoderm, which consists of primitive foetal blood vessels, is seen to extend down into cytotrophoblast columns. Syncytiotrophoblast completely surrounds maternal blood vessels and both basal laminae and endothelial cells of maternal origin show signs of disorganisation and degradation. Syncytiotrophoblast is first observed to breach the maternal circulation in samples collected from animals at 60 days after ovulation; this results in discrete haemochorial villi randomly distributed throughout the placental bed. Samples obtained at 80 days after ovulation and term placental samples (145 days after ovulation) exhibit tertiary haemochorial villi throughout the placenta, similar to those seen randomly distributed at 60 days after ovulation.
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  • 78
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 181 (1990), S. 75-82 
    ISSN: 1432-0568
    Schlagwort(e): Anuran lymph hearts ; Development ; Ultrastructure ; Myogenesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The early development of anuran posterior lymph hearts studied by light- and electron-microscopy in frog larval stages 25–29 (Gosner 1960) can be subdivided into three phases. In phase I, mesenchymal myogenic cells are found, each possessing a single 9 + 0 cilium and numerous filopode-like processes aggregated near the vena caudalis lateralis, forming up to three metameric organ anlagen arranged like a cuff around the preexisting lymphatics (stages 26/27). In phase II, cell proliferation starts at stage 28 within the lymph heart wall as does the formation of primarily polynuclear myofibres by fusion of several myoblasts. At this stage immature myofibres show a vast sarcoplasm, a poorly developed SR and only few myofibrils with not yet distinguishable A- and I-bands. In phase III, the afferent and efferent valves are formed at the onset of pulsation in stage 29. Contractile myofibres contain large glycogen fields and a considerable amount of myofibrils which frequently branch and show distinct Z-lines, A-, I-, H- and M-bands; 1–3 cilia were found lying within a channel-like cell invagination. The peculiarities of organogenesis and myofibre development are discussed.
    Materialart: Digitale Medien
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  • 79
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 79 (1990), S. 456-460 
    ISSN: 1432-0533
    Schlagwort(e): Rosenthal fibers ; Immunohistochemistry ; Ultrastructure ; Neoplastic and reactive astrocytes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The nature of Rosenthal fibres (RF) was investigated in eight cases each of low-grade astrocytoma and reactive gliosis using immunohistochemical (IH) staining for glial fibrillary acidic protein (GFAP), electron microscopy (EM) and immunoelectron microscopy (IEM) by immunogold labelling technique. By IH under light microscopy (LM), three types of RF were seen, uniformly positive (type I), rim positive (type II) and completely negative (type III). EM showed variation in structural pattern of RF. Some RF contained large amount of glial filaments (GF) intermingled with RF while others with a large amount of electron dense material and less GF. Thus, the presence and amount of GF in RF appear to be responsible for the different types of IH staining under LM. IEM showed that all RF including the ones consisting of entirelh amorphous material possess immunoreactivity for GFAP. It is suggested that RF formation is a two-stage process, staring with excessive accumulation of GF within astrocytic processes followed by their gradual alteration into electron-dense amorphous material under the influence of some unknown metablic or other factors. The quantitative analysis of different types of RF suggests a difference in the rate of formation of RF in neoplastic and reactive conditions.
    Materialart: Digitale Medien
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  • 80
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 79 (1990), S. 551-557 
    ISSN: 1432-0533
    Schlagwort(e): Cutaneous nerves ; Neuropathy ; Ultrastructure ; Herpesvirus ; Rabbits
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A light and electron microscopic study was undertaken to determine pathological changes in cutaneous spinal nerves of rabbits following intradermal inoculation with alphaherpesvirus saimiri (αHVS) isolate KM 322. Infected rabbits were killed at 3, 10, 17, 45 days and 2 years after infection. No abnormalities were seen at 3 days postinoculation. In the nerves of the rabbits killed at 10, 17 and 45 days after infection, axonal (Wallerian-type) degeneration was the main pathological feature. Regeneration, manifested by axonal sprouting, was observed in the nerves of the rabbits killed at 45 days post-inoculation. Neural fibrosis and paucity of unmyelinated axons was the final outcome. The severity of the neural damage not only varied according to the progression of the disease but between nerves taken from the same rabbit. This was probably associated with variation in the numbers of virus particles that had reached the dorsal root ganglion of the dermatome served by a particular nerve. Since αHVS (isolate KM 322) provides a model system for the study of virus latency in dorsal root ganglia, and consequently for the study of varicellazoster infection in man, these findings give further insight into the pathology of herpetic neuropathy.
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  • 81
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 80 (1990), S. 255-259 
    ISSN: 1432-0533
    Schlagwort(e): Meningioma ; Phospholipid ; Psammoma ; Ultrastructure ; Chromatography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Phospholipids in meningiomas were studied by light and electron microscopy, and by high-performance liquid chromatography. They were microscopically demonstrated in six of the ten cases by Sudan III staining after the fixation with potassium dichromate. However, the conventional ultrastructural fixation with glutaraldehyde and osmium tetroxide failed to confirm phospholipids, as most of them were dissolved during dehydration. In contrast, the specimens pretreated with tannic acid before osmication ultrastructurally retained phospholipids which were represented by multilamellar bodies or ribbon-like rings. Both were found in 23 of the 30 cases within the cytoplasm, among the plasma membranes and in the extracellular matrices. The outermost lamella or ribbon showed a direct continuity from the neighbouring plasma membranes of the cytoplasm or the mitochondria. The multilamellar bodies showed an overall distribution, while the ribbon-like rings were predominantly distributed around the psammoma bodies. Precipitation of hydroxyapatite crystals within the ribbon-like rings resulted in matrix minerals of psammoma bodies. Chromatographical analyses of meningiomas disclosed phospholipids including phosphatidyl ethanolamine, phosphatidyl choline, phosphatidyl serine, sphingomyelin and phosphatidyl inositol in that order. Psammomatous meningiomas contained a higher percentage of phosphatidyl serine than non-psammomatous tumors. Ultrastructural study of synthetic phospholipids adequately treated with tannic acid showed that the multilamellar bodies were similar to phosphatidyl choline, while the ribbon-like rings were similar to phosphatidyl serine. The role of phospholipids in meningiomas is discussed.
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  • 82
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 182 (1990), S. 1-10 
    ISSN: 1432-0568
    Schlagwort(e): Fish ; Muscle growth ; Hyperplasia ; Hypertrophy ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In this EM study of lateral muscle in Dicentrarchus labrax, we observed that during the larval period, growth of the presumptive red and white muscle layers occurs both by hypertrophy (as fibres already present at hatching complete their maturation) and by production of new fibres in germinal zones specific to the two muscle layers. In the first half of larval life the presumptive white muscle increases in thickness by the addition, superficially, of new fibres derived from a germinal zone of presumptive myoblasts lying beneath the red muscle layer. In the second half of larval life new fibres produced in this same zone form the intermediate (or pink) muscle layer. Dorsoventrally the myotome grows throughout larval life, largely by addition of new fibres from germinal zones at the hypo- and epi-axial extremities. Towards the end of larval life all these germinal zones are becoming exhausted, but another source of fibres arises as satellite cells, associated with large-diameter presumptive white muscle fibres, are activated to produce new fibres. The addition of small, new fibres gives the white muscle its mosaic appearance. Morphometric analysis of fibre diameters in the white muscle confirms that whereas these hyperplastic processes are important during the larval and juvenile periods, when growth is very rapid, they have ceased by the time the adult stage is attained. By contrast, fibre hypertrophy continues through into adult life. The presumptive red muscle consists initially of a monolayer of fibres present only near the lateral line, and during larval life it grows hypo- and epi-axially by addition of fibres derived from myoblasts already present in these areas at hatching. Lying superficially to the presumptive red muscle monolayer there is a near-continuous layer of external cells with a “flattened” profile. During the second half of larval life, differentiation of these external cells into myoblasts provides the source of new fibres which are added to the red muscle layer. This process, which occurs initially in the region around the lateral line and later spreads outwards, is responsible for the increase in thickness of the red muscle.
    Materialart: Digitale Medien
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  • 83
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 182 (1990), S. 41-52 
    ISSN: 1432-0568
    Schlagwort(e): Lamprey ; Pronephros ; Ultrastructure ; Regression ; Apoptosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The regression of the pronephric kidney of the lamprey, Petromyzon marinus, is described using histochemical and ultrastructural techniques. Regression begins in the third year of larval life, and by the time the animal enters metamorphosis the tubules have all disappeared. The nephrostomes and the renal corpuscle, however, persist for the remainder of the life cycle and undergo little change in the larva. Iron is present within the tubular epithelium prior to the beginning of degeneration, but as degeneration proceeds iron is observed within the tubule lumina. Acid phosphatase is noted within the tubule epithelia prior to degeneration, but as degeneration proceeds acid phosphatase is also observed within the intertubular area. Features of tubular regression include a prominent and highly folded basal lamina, numerous cytoplasmic inclusions, and dense bodies in the epithelia and lumina. The intertubular region is invaded by lymphocytes, granulocytes, plasma cells, and macrophages. The process of pronephric regression possesses many features of the process of apoptosis, which has been noted in the regression of larval organs in other vertebrates.
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  • 84
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 181 (1990), S. 491-498 
    ISSN: 1432-0568
    Schlagwort(e): Serotonin ; Ultrastructure ; Caudal Neurosecretory Complex ; Neuroendocrine ; Monoamines
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The caudal neurosecretory complex (CNc) of poecilids has previously been shown to receive serotonergic inputs. In the present study, immunohistochemical techniques were applied at the light and electron microscopic levels to characterize serotonergic terminals in the neuroendocrine nucleus. A dense plexus of varicose fibers observed in the rostral CNc neuropil was absent in the spinal cords of deafferented fish, indicating that the origin of this input was extranuclear. Ultrastructural study revealed no direct contacts between labeled structures and neuroendocrine cells. Non-synaptic terminals (varicosities) were the predominantly labeled structures in the neuropil. Synaptic terminals were observed on cellular and axonal targets in the CNc. Small cells containing 70 nm dense-core vesicles received serotonergic input on their perikarya. Labeled synapses were also found on unlabeled axon terminals which made axoaxonal synapses on neuroendocrine processes. Non-synaptic terminals may be responsible for a variety of serotonin-mediated effects in the CNc. Synaptic interactions with local catecholaminergic and afferent cholinergic inputs to the CNc are likely.
    Materialart: Digitale Medien
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  • 85
    ISSN: 1432-0568
    Schlagwort(e): Mandibular condyle ; Articular tissue layer ; Ultrastructure ; Maturation ; Load-dependence ; Macaca fascicularis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In an attempt to establish maturational alterations in the morphology of the articular tissue layer, mandibular condyles of four immature and four mature male monkeys (Macaca fascicularis) were studied using light microscopy as well as scanning and transmission electron microscopy. Specimens were fixed in situ by perfusion in the presence of ruthenium red to stabilize proteoglycans. Preparations intended for observation in the scanning electron microscope were first dehydrated and sputtered for the examination of articular surfaces, and afterwards treated with trypsin to expose the spatial arrangement of collagen fibrils. Gross anatomical relations between joint components indicated that the anterior and central, but not the posterior region of the condylar articular surface can be subject to compressional load. Load-bearing and non-load-bearing regions differed with respect to the morphology of the articular layer. Load-bearing surfaces were covered by a prominent articular surface lamina similar to that observed on articular cartilage. This lamina seemed to constitute an integral part of the articular layer, distinct from the lining of synovial fluid, and to be composed largely of proteoglycans. It was unaffected by maturation. The subjecent, load-bearing articular layer differed markedly in structure, both from articular cartilage, and between immature and mature animals. Articular cells of immature animals were classified as fibroblastlike, but unlike typical fibroblasts, were surrounded by a thin, often incomplete halo of fibril-free pericellular matrix, presumably consisting of proteoglycans. In mature animals, articular cells closely resembled chondrocytes, but exhibited prominent nuclear fibrous laminae, which usually are found only in fibroblasts. Thus, the load-bearing part of the articular layer seems to undergo a maturation-dependent metaplastic conversion, from a dense connective tissue with some features of fibrocartilage, to a fibrocartilage-like tissue containing chrondrocytelike cells with some features of fibroblasts. This conversion might reflect an adaptation to a maturation-associated increase in articular stress.
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  • 86
    ISSN: 1432-069X
    Schlagwort(e): Dysplastic naevi ; Superficial spreading melanoma ; Naevocellular naevi ; Ultrastructure ; Melanosomes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Eleven dysplastic melanocytic naevi with various degrees of dysplasia, as judged by light microscopy, were studied by transmission electron microscopy, and their intra-epidermal melanocytes compared with those of five superficial spreading melanomas and seven common benign naevocellular naevi. Intra-epidermal melanocytes in dysplastic naevi exhibited signs of cellular atypia, which were most pronounced in the dysplastic naevi with histological high-grade dysplasia. A correlation between the degree of dysplasia at the light microscopic level and the degree of cytological atypia at the ultrastructural level was noted, and melanocytes in dysplastic naevi with a high degree of dysplasia had ultrastructural features similar to the melanocytes in superficial spreading melanomas. Our observations support the concept that dysplastic naevi fill the biological gap between benign naevocellular naevi and malignant melanomas and suggest that at least some of the dysplastic naevi must be regarded as potential precursor lesions of malignant melanoma, particularly those exhibiting a high degree of histological dysplasia.
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  • 87
    Digitale Medien
    Digitale Medien
    Springer
    Archives of dermatological research 282 (1990), S. 108-114 
    ISSN: 1432-069X
    Schlagwort(e): Porphyria ; Dermal vessels ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The skin of 20 patients with variegate porphyria (VP) was studied using light, fluorescent, and electron microscopy. Twelve patients had skin symptoms and markedly increased fecal protoporphyrin excretion. Their sun-exposed skin was characterized by homogeneous PAS-positive thickening and IgG deposition in the vessel walls. The basic ultrastructural change was thickening of the vascular walls caused by reduplication of the basal lamina and perivascular deposition of amorphous material. Qualitatively similar but less prominent histopathological changes occurred in sun-protected skin in some of the patients. Six patients had no skin symptoms but an increased porphyrin excretion. The light microscopical changes were comparable to those in the patients with skin symptoms, but the ultrastructural changes were less severe. No abnormal histopathological changes occurred in two symptomless patients who had low lymphocyte protoporphyrinogen oxidase activity but normal fecal porphyrin excretion. These results show that the primary site of skin damage in VP is the vessel wall, and that histopathological changes of the skin also occur in porphyric patients who have never had skin symptoms. Factors determining the occurrence of skin symptoms in VP are discussed.
    Materialart: Digitale Medien
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  • 88
    Digitale Medien
    Digitale Medien
    Springer
    Archives of dermatological research 282 (1990), S. 434-441 
    ISSN: 1432-069X
    Schlagwort(e): Hair cycle ; Human hair follicle ; Connective tissue sheath ; Hyaline membrane ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Ultrastructural changes of the connective tissue sheath (CTS), including the hyaline membrane, of human hair follicles during the hair cycle, were studied in normal scalp skin specimens. In early anagen, the CTS was composed of a thin basal lamina and surrounding collagen tissue. The collagen tissue gradually thickened during the development of the hair and hair follicle. In mature anagen hair follicles, the collagen tissue was separated into three layers. The inner collagen layer, just outside the basal lamina, was thin and composed of collagen fibres running longitudinally parallel to the hair axis. The middle collagen layer was very thick with its collagen fibres running transversely against the hair axis and surrounding the inner hair tissue. Many fibroblasts were present among the collagen fibres in the middle layer, whereas the inner layer contained almost none. In the outer collagen layer, collagen fibres ran in various directions parallel to the outer surface of the outer root sheath cells. In late anagen, the basal lamina became very thick. In catagen, the basal lamine and the inner collagen layer became corrugated and showed oedematous change and degeneration. Surrounding fibroblasts showed active production of new collagen fibres, which seemed to fill the spaces left by the retraction of the hair follicle and hyaline membrane. These ultrastructural changes of the CTS show that there may be dynamic metabolic changes of the connective tissue around human hair follicles during the hair cycle.
    Materialart: Digitale Medien
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  • 89
    ISSN: 1432-072X
    Schlagwort(e): Intercellular junctions ; Multicellularity in prokaryotes ; Bacterial magnetotaxis ; Ultrastructure ; Bacterial co-ordination
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A many-called magnetotactic prokaryote obtained from brackish water was observed to possess intercellular connections at points of contact between the outer membranes of constituent cells. Each aggregate organism consisted of 10 to 30 individual Gram-negative cells containing material with the appearance of poly-β-hydroxybutyrate and magnetosomes of unusual arrangement, structure and composition. The aggregate, which possessed prokaryotic-type flagella arranged at the outwards surfaces of each cell, showed motility indicative of co-ordination between individual component cells. These results suggest that this organism could be a multicellular prokaryote.
    Materialart: Digitale Medien
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  • 90
    Digitale Medien
    Digitale Medien
    Springer
    Journal of cancer research and clinical oncology 116 (1990), S. 517-524 
    ISSN: 1432-1335
    Schlagwort(e): Tumor vascularization ; Tumor blood flow ; Xenograft ; Nude mouse ; Vascular corrosion cast ; Ultrastructure ; Electron microscopy ; Heterogeneity ; Vessel morphology ; Morphometry ; Necrosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary This study was designed to examine the vascular system of human xenotransplanted tumors on nude mice with different complementary morphometrical and morphological methods. The vascular system shows a chaotic arrangement. There is an extreme heterogeneity in the vascular distribution and density. Large avascular regions could be identified in several non-necrotic tumors. There was no clear difference in the vascular density between the center and the periphery of the tumors, nor was there any zonal correlation for the distribution of the necrosis. With three-dimensional corrosion casts it could be demonstrated that clusters of vessels were directly beneath areas almost free of vessels. In the center, vessels often form a sinusoidal system with numerous blind ends without clearly discernible endothelial cells. Numerous irregular tumor-cell-lined sinusoids are visible next to endothelial-lined vessels with transmission electron microscopy. With scanning electron microscopy it could be demonstrated that large-calibre endotheliazed vessels were found in the direct vicinity or in the center of non-viable zones. Even large-calibre vessels have a capillary wall structure. Sometimes, a basement membrane cannot be observed at all or only incompletely. There are numerous indications of vascular discontinuities and leaks with a widespread intercellular occurrence of blood cells.
    Materialart: Digitale Medien
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  • 91
    ISSN: 1432-0878
    Schlagwort(e): Adrenal cortex ; Tissue culture ; Corticosterone ; Ultrastructure ; Lipoproteins ; Mevinolin ; Rat (Sprague-Dawley)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The present study was undertaken to define the effects of lipoprotein-derived cholesterol and endogenous, de novo synthesized cholesterol on the ultrastructure and function of undifferentiated rat adrenocortical cells [lipoprotein (HDL3 and LDL) receptor-negative, zona glomerulosa-like adrenocortical cells] in primary culture. For this purpose human plasma high density lipoprotein (HDL3) or low density lipoprotein (LDL) was added to culture medium devoid of cholesterol. Steroid secretion remained at the low basal level even after addition of lipoproteins, and the amount of intracellular lipid droplets did not increase. When mevinolin (0.96 µg/ml), an inhibitor of cholesterol synthesis, was added to the culture medium, a low secretion of corticosterone was measured both in serum-free and serum-containing media. Ultrastructurally, lipid droplets disappeared after treatment with mevinolin in both media used. At this concentration of mevinolin cell proliferation was similar to that in the controls, but at higher concentrations (4.8 or 9.6 µg/ml) proliferation was inhibited to 42% and 26% in serum-free medium, and 20% and 12% in serum-supplemented medium, respectively. This study demonstrates that cell proliferation and synthesis of corticosterone by undifferentiated rat adrenocortical cells is identical in the absence or presence of exogenous lipoprotein cholesterol. Inhibition of de novo cholesterol synthesis by mevinolin over a period of 7 days does not inhibit corticosterone secretion or proliferation of cells but decreases the amount of intracellular lipid droplets, thus suggesting utilization of intracellular cholesterol esters. However, higher concentrations of mevinolin inhibit proliferation of cells both in serum-free and serum-containing media.
    Materialart: Digitale Medien
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  • 92
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 260 (1990), S. 495-505 
    ISSN: 1432-0878
    Schlagwort(e): Cuticle ; Epithelium, branchial ; Gills ; Hemocoel ; Histology ; Ultrastructure ; Carcinus maenas (Crustacea)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The phyllobranchiate gills of the green shore crab Carcinus maenas have been examined histologically and ultrastructurally. Each gill lamella is bounded by a chitinous cuticle. The apical surface of the branchial epithelium contacts this cuticle, and a basal lamina segregates the epithelium from an intralamellar hemocoel. In animals acclimated to normal sea water, five epithelial cell types can be identified in the lamellae of the posterior gills: chief cells, striated cells, pillar cells, nephrocytes, and glycocytes. Chief cells are the predominant cells in the branchial epithelium. They are squamous or low cuboidal and likely play a role in respiration. Striated cells, which are probably involved in ionoregulation, are also squamous or low cuboidal. Basal folds of the striated cells contain mitochondria and interdigitate with the bodies and processes of adjacent cells. Pillar cells span the hemocoel to link the proximal and distal sides of a lamella. Nephrocytes are large, spherical cells with voluminous vacuoles. They are rimmed by foot processes or pedicels and frequently associate with the pillar cells. Glycocytes are pleomorphic cells packed with glycogen granules and multigranular rosettes. The glycocytes often mingle with the nephrocytes. Inclusion of the nephrocytes and glycocytes as members of the branchial epithelium is justified by their participation in intercellular junctions and their position internal to the epithelial basal lamina.
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  • 93
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 260 (1990), S. 601-616 
    ISSN: 1432-0878
    Schlagwort(e): Autonomic ganglia ; Catecholamines ; Intestines ; Innervation ; Ultrastructure ; Domestic fowl (Aves)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary An ultrastructural study was made of the neurons, satellite cells and vesiculated axons of the intestinal nerve of the domestic fowl. Broad membrane-to-membrane contacts between adjacent nerve cell bodies were sometimes observed. The cell bodies and processes were not always separated from the extracellular space by a capsule of satellite cells. Following fixation using potassium permanganate, catecholamine (CA)-containing neurons in the intestinal nerve, unlike those in the lumbar parasympathetic ganglia, did not possess any small granular vesicles (SGV). Following exposure to noradrenaline, SGV could be demonstrated in the cell bodies of the juxta-ileal ganglia but not the juxta-rectal ganglia of the intestinal nerve. Non-CA axons were examined in tissue from birds that had been pretreated with 6-hydroxydopamine. Approximately one half of the non-CA axons formed axo-somatic contacts. Most of the non-CA axons contained varying proportions of small clear vesicles, large clear vesicles and large granular vescles. Statistical analysis showed that the non-CA axons could not be subdivided according to their vesicle content. CA-axons contained many SGV and were found in close apposition to neuronal somata and processes, and in the neuropil.
    Materialart: Digitale Medien
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  • 94
    ISSN: 1432-0878
    Schlagwort(e): Stomach ; Enteroendocrine cells ; Enterochromaffin-like (ECL) cell ; Enterochromaffin cell (EC) ; Histamine ; Ultrastructure ; Secretory granules ; Didelphis albiventris (Marsupialia)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary An ultrastructural study of enterochromaffin-like (ECL) cells in the gastric mucosa of the white-belly opossum Didelphis albiventris (Marsupialia) was carried out. In parallel, histochemical methods were used at the light-microscopical level to demonstrate argentaffin cells, argyrophilic cells, and serotonin- and histamine-immunoreactive elements. Argentaffin and serotonin-immunoreactive cells were scattered, and argyrophilic cells were numerous, within the full thickness of the mucosa. Argyrophilic cell distribution was similar to that of histamine-immunoreactive elements. At the electron-microscopical level, the oxyntic mucosa of D. albiventris presented endocrine cells with secretory granules morphologically similar to those of the ECL cell of eutherian mammals. However, in this marsupial, the ECL cell exhibited a variable mixture of two distinct types of secretory granules: (1) granules with the morphological appearance of the eutherian ECL cell, and (2) granules morphologically similar to those of the eutherian enterochromaffin (EC) cells. Based on this morphological pattern of the ECL cell granules, it is proposed that in the oxyntic mucosa of the opossum D. albiventris, the EC and ECL cells represent distinct steps in the same line of cell differentiation; the ECL cell should also be a site of histamine storage.
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  • 95
    ISSN: 1432-0878
    Schlagwort(e): Adrenal cortex ; Differentiation ; Tissue culture ; Mevinolin ; Steroids ; Ultrastructure ; Rat (Sprague-Dawley)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Mevinolin, an inhibitor of cholesterol synthesis, was used to study the effect of endogenous cholesterol synthesis on the morphology and function of differentiating and differentiated fetal rat adrenocortical cells grown in primary culture. Upon adrenocorticotrophic hormone (ACTH) stimulation under conditions in which endogenous cholesterol synthesis was inhibited but exogenous (lipoprotein) cholesterol was available, the cells differentiated normally from glomerulosa-like to fasciculata-like cells; the steroid hormone secretion was maximally induced. Under conditions in which cholesterol synthesis was maximally inhibited by mevinolin and the cells had no access to exogenous cholesterol, the cells did not differentiate into fasciculata-like cells; the ACTH-induced steroid response was highly suppressed under these conditions. The addition of either human low-density lipoprotein (LDL) or high-density lipoprotein (HDL3) to the culture medium restored the ACTH-induced differentiation and steroid secretion. Thus, in the absence of exogenous cholesterol, endogenous cholesterol synthesis was a prerequisite for differentiation. In cultures grown in the presence of exogenous cholesterol and ACTH with mevinolin-inhibited cholesterol synthesis and high steroid output, an increase in cytoplasmic lipids was evident, suggesting upregulation of LDL and HDL receptors. The results also demonstrated that induction of phenotypic differentiation from glomerulosalike into fasciculata-like cells can proceed in the presence of a cholesterol synthesis inhibitor like mevinolin; this differentiation in the absence of endogenous cholesterol synthesis is accompanied by the appearance of cytoplasmic cholesterol ester droplets, typical of fasciculata cells.
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  • 96
    ISSN: 1432-0878
    Schlagwort(e): Atrial appendage ; Atrial-specific granules ; Atrial natriuretic polypeptides ; Exocytosis ; Ultrastructure ; Rat (Sprague-Dawley)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Atrial appendage cardiocytes of mammals, including man, contain multiple cytoplasmic granules that vary in number in different physiological states. Using morphologic and comprehensive morphometric techniques, these granules were assessed in Sprague-Dawley rats following dehydration for 5 days, volume-loading by substituting 1% NaCl as drinking water for 7 days, unilateral nephrectomy plus volume-loading for 7 days, and in late term pregnant animals (18–20 days; term ≈21 days). Although principally located in the paranuclear region, granules were observed throughout the sarcoplasm. Cytological features indicative of synthetic activity and granule formation were readily apparent in all groups with the exception of pregnant rats where they were infrequently observed. Granule contents were released by exocytosis and observed in the right appendage of control, dehydrated and nephrectomy/volume-loaded groups and left appendage of volumeloaded animals. Exocytosis was not observed in pregnant animals. By point counting, the proportional volume of cardiocytes occupied by granules (V v ) in controls was significantly greater for right than for left appendage (2.12±0.22% vs 1.29±0.16%; mean±SEM;p〈0.05). A significantly similar difference was found for nephrectomy/volume-loaded animals. There was no significant difference inV v for right appendage between the control and experimental groups; for left appendage there was a significant increase inV v to 2.42±0.09% (p〈0.05) for volume-loaded animals only. Estimation of the maximum diameter of granule profiles in control animals was 238±9 nm and 230±6 nm for right and left appendages, respectively. The profile diameters in the left appendages of dehydrated (202±9 nm) and pregnant (200±7 nm) animals were significantly (p〈0.05) less than those of the control animals. The morphometric findings did not correlate with predictions based upon published biochemical data. In the course of this study, a previously unreported bimembranous, circular to ovoid structure was observed in the cardiocyte sarcoplasm of all animals; the nature and function of this structure is unknown.
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  • 97
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 259 (1990), S. 33-41 
    ISSN: 1432-0878
    Schlagwort(e): Photoreceptor cells ; Ultrastructure ; Volumetric change ; Light/dark cycle ; Lampetra japonica (Cyclostomata)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Short photoreceptor cells of the lamprey retina exhibited a 30% increase in the width of the myoid process and a 20% increase in that of the axonal process during a 12-h light period, compared to the measurements obtained during a 12-h dark period. An increase in the amount of cytoplasm, dilation of ER cisterns, and swelling of the nucleus appeared to cause the enlargement of the myoid parts. Accumulation of synaptic vesicles occurred concurrently with a thickening of the axonal process. These morphological changes presumably represent a phase of the diurnal cycle and current synaptic activity of the short cell. By contrast, the long photorecpetor cell showed neither measurable changes nor any indication of “retinomotor movement”.
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  • 98
    ISSN: 1432-0878
    Schlagwort(e): Cerebrospinal fluid-contacting neurons ; Paraventricular organ ; Posterior recess organ ; Somatostatin ; Serotonin ; Ultrastructure ; Immunocytochemistry ; Dogfish,Squalus acanthias skate,Raja radiata (Elasmobranchii)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The paraventricular organ (PVO) and the posterior recess organ (PRO) of two elasmobranch species, the spiny dogfish,Squalus acanthias, and the skate,Raja radiata, were investigated by use of scanning and transmission electron microscopy and immunocytochemistry employing a series of primary antisera. The PVO and PRO contained four types of cerebrospinal fluid (CSF)-contacting neurons. One type was free of secretory granules and projected a dendrite-like process into the ventricle. The other three types were distinguished according to the size of their secretory granules. The ventricular extensions of these cells were filled with secretory granules. By means of immunocytochemistry three types of CSF-contacting neurons were observed in the PVO and PRO. Type I contained only serotonin; type 2 displayed only somatostatin; type 3 was endowed with both serotonin and somatostatin. Type I dominated in the PRO, whereas type 3 was the most frequent in the PVO. The latter cells appear to be the site of origin of a loose tract formed by serotonin- and somatostatinimmunoreactive fibers projecting from the PVO into the neuropil of the PRO. Compact bundles formed exclusively by serotonin fibers were also shown to extend between the PVO and PRO. The basal processes of the CSF-contacting neurons of the PRO penetrated into the underlying neuropil. This neuropil is rich in synapses and can be regarded as an integrative area to which the basal processes of the local CSF-contacting neurons, serotonin and somatostatin fibers from the PVO, and fibers containing immunoreactive thyrotropin-releasing hormone of unknown origin, support a conspicuous input. The present findings indicate that the PVO and PRO of elasmobranchs are functionally integrated structures.
    Materialart: Digitale Medien
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  • 99
    ISSN: 1432-0878
    Schlagwort(e): Median eminence ; Catecholamines ; Neuropeptides ; Immunocytochemistry ; Double labeling ; Ultrastructure ; Triturus alpestris (Urodela)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Dopaminergic and peptidergic nerve fibers were simultaneously demonstrated with a double-labeling technique at the ultrastructural level. The first antibody, raised against tyrosine hydroxylase, was applied during the preembedding phase and visualized with the peroxidase method. The second antibody, raised against one of the peptides met-enkephalin, somatostatin or gonadotropin-releasing hormone (GnRH), was applied to the ultrathin sections and visualized with gold-labeled goat anti-rabbit IgG. The fibers of both categories were present in the zona externa of the median eminence, frequently contacting the basal lamina of the portal vessels. In addition, topographical relationships between different types of nerve fibers were observed in the perivascular areas, although there were no morphological signs of synaptic specializations. Using serial sections, it could be established that one GnRH-fiber contacted both a dopaminergic fiber and a fiber immunoreactive for met-enkephalin. The observations support earlier physiological data concerning the regulation of the hypothalamo-hypophyseal axis, with special emphasis on the release of neurohormones in the median eminence of the newt.
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  • 100
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 259 (1990), S. 599-602 
    ISSN: 1432-0878
    Schlagwort(e): Crystalloids ; Filaments ; Sertoli cells ; Testis ; Ultrastructure ; Three-toed sloth,Bradypus tridactylus (Edentata)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Crystalloids were found in Sertoli cells of the testis of the three-toed sloth by examination at the lightand electron-microscopic levels. Needle-, or spindle-shaped crystalloids, varying in length, were located in the basal part of the Sertoli cells. They consisted of bundles of filaments each measuring ~ 11 nm in diameter. Several filaments were packed hexagonally to form a bundle. The center-to-center distance between individual filaments of a bundle was ~ 17 nm. Periodical lateral projections emanated from the filaments. Cross sections of crystalloids showed that the projections radiated from each filament in three directions, forming an equilateral triangle with a side length of ~ 15 nm. Scattered polyribosomes were found between and around the bundles.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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