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  • 1995-1999  (38)
  • 1970-1974  (115)
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  • 1999  (38)
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  • Ultrastructure  (153)
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  • 1995-1999  (38)
  • 1970-1974  (115)
  • 1920-1924
  • 1880-1889
  • 1800-1809
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  • 1
    ISSN: 1437-773X
    Keywords: Key words Heart ; Ultrastructure ; Capillaries ; Endothelium ; Stereology ; Cardioplegic solutions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In open heart surgery and transplantation, sufficient structural preservation of the myocardium immediately following cardioplegic arrest is a precondition for overcoming ischemia and for resumption of postischemic function. Therefore, we compared the protective effect of three clinically applied cardioplegic solutions with fibrillating and beating hearts using structural criteria. Left ventricular samples were taken from (1) beating, or (2) fibrillating or arrested hearts following coronary perfu-sion with (3) St. Thomas' Hospital solution, (4) histidine tryptophane ketoglutalate (HTK) (Custodiol), or (5) University of Wisconsin (UW) solution and fixed by immersion. Ultrastructural differences in the swelling of capillary endothelial cells and myocytes were quantitatively evaluated using stereological methods. Endothelial cells were somewhat more swollen after St. Thomas perfusion than those in beating and fibrillating hearts. HTK-arrested hearts showed significantly lower values for cellular edema than beating hearts. UW perfusion resulted in the (significantly) lowest degree of endothelial cell edema. Edematous changes in myocytes were significantly greater in St. Thomas-arrested hearts than in UW- or HTK-arrested hearts. Cardiomyocyte edema in beating and fibrillating hearts was comparable to that in St. Thomas-perfused hearts. Thus, the stereol-ogical analysis revealed significant differences between cardioplegic solutions in structural preservation of myocardial ultrastructure.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1437-773X
    Keywords: Key words: Secretory carcinoma ; Breast ; Intracytoplasmic lumina ; Immnohistochemistry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report a rare case of secretory carcinoma of the breast in a 50-year-old Japanese woman. The patient had been aware of a right breast tumor for 8 years, but had left it untreated. The tumor enlarged in size and became painful, and she visited our hospital. Breast carcinoma was diagnosed, and mastectomy was performed. Histopathological examination revealed features of a secretory carcinoma characterized by prominent secretory activity in the glandular and microcystic spaces, with some areas showing a follicular pattern resembling the thyroid gland. The secretory material was PAS-positive and immunohistochemically α-lactalbumin-positive. Ultrastructurally, the tumor cell contained many secretory vacuoles in the cytoplasm. In addition, extracellular and intracytoplasmic lumina were conspicuous; these were lined by microvilli projection and contained secretory material. By flow cytometric analysis, the DNA index was 1.14, which was diploid, showing relatively low proliferative activity.
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  • 3
    ISSN: 1437-773X
    Keywords: Key words KSHV ; HHV-8 ; TPA ; Ultrastructure ; Primary effusion lymphoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The ultrastructure of Kaposi's sarcoma-associated herpesvirus (KSHV)/human herpesvirus-8 (HHV-8) has not yet been fully elucidated, although some findings have been reported using primary effusion lymphoma (PEL) cell lines, KS-1, harboring no Epstein–Barr virus (EBV) coinfection. In the present study, detailed fine structural examination of KSHV/HHV-8 was performed after stimulation of the PEL-derived cell line KS-1 with 12-O-tetradecanoyl-phorbol-13-acetate (TPA) in vitro. While unstimulated KS-1 cells contained a small number of intranuclear virus particles associated with no extracellular mature particles, KS-1 cells stimulated with TPA produced many extracellular mature particles as well as intranuclear particles, in addition to interesting tubulo-reticular structures and aggregated tubular structures in vesicles. The induced intranuclear particles were empty, doughnut shaped, and dense cored, with outer and inner diameters of 100–110 nm and 60–70 nm, respectively. Dense-cored extracellular mature particles were 150–160 nm in diameter, and some contained doughnut-shaped cores, together with a few megaloviruses, 260 nm in outer diameter. These findings indicate that KS-1 cells treated with TPA can produce extracellular mature particles as well as intranuclear particles, which were proven to be KSHV/HHV-8.
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  • 4
    ISSN: 1437-773X
    Keywords: Key words pHGF ; HGF ; Acute liver injury ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The protective effect of hepatocyte growth-promoting factor (pHGF) against CCl4-induced acute hepatitis in rats was examined by light and electron microscopy. Hepatocyte growth-promoting factor, purified from infant pig liver in an active form, has been used clinically in patients with hepatitis in China. Four hours after administration of CCl4, a single dose of pHGF was administered intraperitoneally. Six hours after administration of CCl4, inhibition of CCl4-induced hepatic necrosis and hepatocytes with severely dilated endoplasmic reticula were evident in rats treated with pHGF. At 48 h post administration, most hepatocytes had recovered, and not only mitotic hepatocytes (10–13 mitotic cells/100) but also mitotic Kupffer cells were observed. At 72 h, it was evident that the differentiation of hepatic stellate cells (Ito cell) into myofibroblast-like cells and the development of fibrosis around the central veins was prevented by pHGF. These results suggested that (1) pHGF may stabilize cell membranes, (2) pHGF acts as a mitogen not only for hepatocytes but also for Kupffer cells, and (3) pHGF prevents fibrogenesis in the case of CCl4-induced liver injury by preventing the differentiation of hepatic stellate cells.
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  • 5
    ISSN: 1437-773X
    Keywords: Key words Cerebral blood flow ; Blood–brain barrier ; Repeated brief cerebral ischemia ; Hippocampal CA1 ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Neuronal damage and changes in cerebral blood flow (CBF) and the permeability of the blood–brain barrier (BBB) following repeated brief periods of ischemia were studied in Mongolian gerbils. The cerebral ischemia was produced by three repeated occlusions of bilateral common carotid arteries for 3 min at 1-h intervals. CBF and permeability of the BBB were examined with tracers (China ink and silver nitrate) at 1, 3, and 7 days post ischemia using light and electron microscopy. Three days after the reperfusion, significant extravasation of tracers, consequential reduction of CBF, extensive neuronal destruction, and intravascular platelet aggregation were observed. Such vascular changes in the CA1 region were more severe than those in the frontal cortex. These findings strongly support the view that microcirculatory disturbance may be a mechanism responsible for delayed neuronal death in the CA1 region of the hippocampus.
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  • 6
    ISSN: 1432-2307
    Keywords: Key words Inflammation of the lung ; Biopsy ; Ultrastructure ; Laser therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Examination of 127 biopsy specimens from 45 patients with inflammatory lung diseases showed changes consistent with increased permeability of the capillary endothelial cells as an initial stage in the development of the inflammatory reaction. Associated interstitial oedema, deformation of the interalveolar septa, and structural disorganization of alveolar epithelium cells occur, and local microcirculatory problems result in tissue hypoxia and fibrosis. The ultimate morphological picture is determined largely by the intensity of repair. Laser biostimulation minimizes the inflammation and stabilizes fibroplastic process.
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  • 7
    ISSN: 1432-2307
    Keywords: Key words Capillary basement membrane ; Inflammatory myopathy ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The capillary basement membranes from 16 skeletal muscle biopsies from patients with a clinical and histological diagnosis of inflammatory myopathy and from six controls were analysed ultrastructurally and morphometrically. Resin sections from 244 endomysial capillaries were examined by light microscope, and the results were correlated with findings seen in electron micrographs of these capillaries. The ultrastructural morphometric measurements and the statistical analysis showed that the capillary basement membrane was thick and multilaminated in 87% specimens affected by inflammatory myopathy. No thick or multilaminated basement membrane was observed in controls. In inflammatory myopathy the endomysial space next to the capillaries contained an increased amount of collagen fibrils and showed signs of a chronic reparative process. It is suggested that the thick multilaminated basement membrane in inflammatory myopathy represents an advanced stage of vascular regeneration.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Urological research 27 (1999), S. 454-461 
    ISSN: 1434-0879
    Keywords: Key words Cold-restraint stress ; Urinary bladder ; Interstitial cystitis ; Mast cell ; Urothelium ; Ultrastructure ; Ruthenium red ; Flow cytometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Stress is associated with many diseases of unknown aetiology. This study demonstrates the effects of cold-restraint stress on the morphology of the urinary bladder. Additionally, it compares the results obtained with the morphology of the interstitial cystitis. The animals were subjected to three hours of cold-restraint stress and then starved for 48 h. The morphology and histochemistry of the urinary bladder was investigated with light and electron microscopy. The proliferative activity was analysed via flow cytometry. Increased and degranulated mast cells in the mucosa, leucocyte infiltration in the lamina propria, vacuole formation in the urothelial cells, loose tight junction, dilated intercellular spaces and altered proliferative activity were observed in the stress group when compared with the control. The increase in the number of mast cells and especially degranulated mast cells and vacuole formation and the loose tight junction of the urothelium correlated with the histopathological findings of interstitial cystitis.
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  • 9
    ISSN: 1432-0533
    Keywords: Key words Amyotrophic lateral sclerosis ; Bunina body ; Guam ; Immunohistochemistry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract An investigation of Bunina bodies is important when studying the pathoetiology and pathomechanisms involved in amyotrophic lateral sclerosis (ALS). It may serve as a clue essential for the study of the pathogenesis of Guamanian amyotrophic lateral sclerosis (ALS-G), and it may provide a means of answering the question of whether ALS-G is the same disease as classical ALS or a different entity. In ALS-G, however, no precise histochemical, immunohistochemical, or detailed ultrastructural examination has been published to date. To elucidate the pathological differences/similarities of Bunina bodies between classical ALS and ALS-G, we performed histochemical, immunohistochemical, topographic and ultrastructural examinations. Histochemically, hematoxylin and eosin, Masson’s trichrome, methylgreen-pyronin, phosphotungstic acid-hematoxylin, Klüver-Barrera, Bodian and periodic acid-Schiff staining were utilized. Immunohistochemical examination was performed using antibodies for cystatin C, ubiquitin, Tau-2, Cu/Zn superoxide dismutase, phosphorylated neurofilament and glial fibrillary acidic protein. Histochemical findings were consistent with those previously described for classical ALS. The immunohistochemical study showed that in ALS-G Bunina bodies were intensely labeled by an anti-cystatin C antibody. Topographic examination demonstrated that Bunina bodies were distributed in the spinal anterior horns and Clarke’s column in the spinal cord. Ultrastructurally, Bunina bodies were composed of electron-dense amorphous/ granular material accompanied by vesicular structures and neurofilaments. The results of the present study have revealed that the pathological features of Bunina bodies in ALS-G are identical to those seen in classical ALS. These findings strongly suggest that a similar degenerative process occurs in the spinal anterior horn cells in both ALS-G and classical ALS.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 97 (1999), S. 509-514 
    ISSN: 1432-0533
    Keywords: Key words Hereditary inclusion body myopathy ; Desmin storage myopathy ; Ultrastructure ; Immmunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report two adult familial cases of inclusion body myopathy (IBM) with desmin storage in skeletal muscle. Clinically, both patients presented late-onset, progressive, symmetrical, both proximal and distal muscle weakness. Muscle biopsy findings were identical in both cases and consisted of marked variability in fiber size, increased number of central nuclei and vacuolation involving 10% of fibers. Single or multiple vacuoles were located subsarcolemmally or in the center, and were rimmed by basophilic material. At the ultrastructural level, tubulofilamentous nuclear and cytoplasmic inclusions of 16–21 nm in diameter were frequently observed. In addition, large subsarcolemmal and central deposits composed of electron-dense granular material were present in many fibers. Immunocytochemistry revealed staining for desmin, vimentin and ubiquitin within both inclusions and vacuolated fibers. Possible structural and functional associations between these two types of muscle changes remain unclear. They may either represent two coexistent disease processes or merely reflect an abnormal form of muscle fiber degradation, with unidentifiable specificity.
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 200 (1999), S. 81-90 
    ISSN: 1432-0568
    Keywords: Key words Elastic fibre system ; Microfibrils ; Collagen type IV ; Ultrastructure ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  This study deals with the examination of the elastic fibre system as well as collagen fibrils and collagen type IV in the amnion of the human chorionic plate of uncomplicated pregnancies at term. In organs other than placenta, the elastic fibre system comprises elastic fibres, elaunin and oxytalan microfibrils. The investigation was performed by light and electron microscopy and immunocytochemistry. Abundant oxytalan fibres were present in all amnionic layers, while no elastic fibres were found. Oxytalan microfibrils formed a broad subepithelial layer and were intermingled with collagen fibrils in the subjacent compact layer and in the amnionic mesoderm. Light microscopically, bunches containing orcein-stained oxytalan and collagen-type-IV-immunostained microfibrils were seen rising from the amnionic mesoderm perpendicularly towards the epithelial layer, where they obviously inserted. It can be assumed that the subepithelial microfibrillar layer and the following compact layer form an anchoring zone between the amnionic mesoderm and the epithelium that may contribute to the maintenance of strength. The ultrastructure of the bunches clearly showed collagen fibrils mixed with oxytalan microfibrils. No collagen type I-immunostaining was found in the bunches. After pretreatment of cryostat sections with elastase, oxytalan-orcein-staining was absent, but collagen type IV-immunoreactivity was not altered. Furthermore, after oxytalan-orcein-staining resp. anti-collagen type IV incubation, all positive fibres revealed an identical morphological pattern. We propose that oxytalan and collagen type IV may represent further members of the microfibril complex.
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  • 12
    ISSN: 1432-0533
    Keywords: Key words Ischemia ; Protein synthesis ; Translation ; Ultrastructure ; Hippocampus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract During post-ischemic brain reperfusion there is a substantial reduction of protein synthesis in selectively vulnerable neurons. Normal protein synthesis requires a functional translation initiation complex, a key element of which is eukaryotic initiation factor 2 (eIF2), which in a complex with GTP introduces the met-tRNAi. Phosphorylation of Ser51 on the α subunit of eIF2 [eIF2α(P)] generates a competitive inhibitor of eIF2B, thereby preventing the replenishment of GTP onto eIF2, thus blocking translation initiation. It has been shown that the conditional expression of an eIF2α mutant (Asp substituted for Ser51) imitating the negative charge of Ser51 (P) induces apoptosis. During the first 10 min of post-ischemic reperfusion, there is an approximately 20-fold increase in eIF2α(P) seen in the cytoplasm of CA1 hippocampal neurons, and, by 1 h, there is also accumulation of eIF2α(P) in the nucleus. We utilized post-embedding electron microscopical immunogold methods to examine the localization of eIF2α(P) during reperfusion. Immunogold particles (10 nm) were concentrated chiefly along the rough endoplasmic reticulum and in association with the membranes of the nuclear envelope in CA1 neurons. Aggregations of gold particles in the nucleus were concentrated: (1) within and around the nucleolus, (2) associated to strands of heterochromatin, and (3) along putative nuclear filaments. The presence of eIF2α(P) in the nucleolus probably reflects its association with nascent ribosomal subunits. The β-subunit of eIF2 has a zinc finger and polylysine blocks analogous to those on other proteins that affect transcription. The association of eIF2α(P) with chromatin may have important implications for transcription.
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 199 (1999), S. 407-418 
    ISSN: 1432-0568
    Keywords: Key words Placenta ; Vascular wall ; Smooth muscle cell ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The vascular wall structure in the human full-term placental villi of normal pregnancy was studied by means of light and electron microscopy with an improved technique of perfusion fixation and tissue preparation. We observed 81 sections of stem villi that showed cross-sectional profiles of paired vessels in their center. Both vascular walls contained a large amount of extracellular matrix and no elastic lamina between smooth muscle cells of the media, making identification of the artery and the vein quite difficult at first sight. We then noted that the density of the smooth muscle cell population was always considerably higher in one than the other, and identified the former as artery and the latter as vein on the basis of their connection with larger arteries and veins running on the chorionic plate. Between the paired vessels, the artery had a smaller caliber than the vein, and the ratio of venous to arterial caliber was distributed from 1.0 to 2.5. The thickness of media was usually thicker in the vein than in the artery. Clusters of elastic fibers were found occasionally in the media of arteries and veins, and basement membrane-like materials were associated frequently with the elastic fibers and were distributed widely in the media as well as in the adventitia. In the veins, the smooth muscle cells of the most superficial part of the media contained well-developed rough endoplasmic reticulum and Golgi apparatus, indicating differentiation to secrete extracellular matrices. The present study revealed the difference of wall structure between arteries and veins in the placental stem villi for the first time at the ultrastructural level, and suggested differentiation of venous smooth muscle cells, possibly by some influence from the luminal side.
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  • 14
    ISSN: 1432-0533
    Keywords: Key words Polyglucosan body ; Periodic ; acid-Schiff-positive granules ; Mouse brain ; Immunohistochemistry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Periodic acid-Schiff-positive granules (PGs) appear in the mouse brains in relation to advancing age. The exact location and pathophysiological significance of PGs, however, are not fully understood. The incidence, staining properties, and topographical distributions of PGs in the brains of 17 AKR mice ranging in age from 7 to 18 months were examined histochemically and immunohistochemically using antibody KM279 raised against a polyglucosan. In addition, to define the precise site of PG formation, we investigated the brains of 4 AKR mice of 24 months of age using conventional and immunoelectron microscopy. PGs were seen in all mice examined and the levels were increased with age. The PGs were located predominantly in the hippocampus and, to a lesser extent, in the cerebellum and olfactory bulb. Immunohistochemically, PGs in the hippocampus and cerebellum were labeled uniformly with KM279. On immunoelectron microscopy with this monoclonal antibody, the fibrillar or membranous structures corresponding to PGs seen using light microscopy were labeled specifically with gold particles. With conventional electron microscopy, fibrillar or membranous structures were seen along with synaptic vesicles and dense-core granules. Moreover, around the cells containing PGs, a few synaptic junctions with neighboring cells were observed, indicating that the cells contributing to formation of PGs were neuronal cells. The positive immunoreactivity of AKR mouse PGs for the antibody KM279 suggests that the PGs and similar structures in other species may share a common antigenicity. Thus, it is assumed that PGs in AKR mice might result from some abnormalities in glucose metabolism.
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  • 15
    ISSN: 1432-0533
    Keywords: Key words Amyloid precursor protein ; immunoreactivity ; Axonal injury ; Microwave antigen retrieval ; Traumatic brain injury ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Antibodies to the amyloid precursor proteins (APP) have become routine markers for detecting traumatically induced axonal injury (AI) in animals and man. Unfortunately, the techniques used to visualize these proteins are not compatible with routine electron microscopic (EM) analysis. In the current communication, we describe a method for the ultrastructural visualization of antibodies to APP and, using this method, we identify a previously unrecognized population of traumatically injured axons. Rats were subjected to an impact acceleration traumatic brain injury and allowed to survive 30 min to 3 h postinjury. The animals were then perfused, their brains sectioned on a vibratome and the sections prepared for immunocytochemistry using a computer-controlled microwave capable of temperature regulation. The use of temperature-controlled microwave energy unmasked APP antigenic epitopes without sacrificing ultrastructural detail. The APP antibody was found in two distinct populations of reactive axons that differed in size, morphology, location, and temporal progression. Comparable to previous descriptions, one population showed traumatically related reactive changes that led to swelling and disconnection. The other population, however, revealed unanticipated changes reflected in nodal and paranodal swelling of small continuous fibers that showed no evidence of disconnection during the time periods assessed. These studies provide new insight into the complexity of the pathobiology of AI, while describing a novel approach for enhancing APP immunoreactivity at the EM level.
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  • 16
    ISSN: 1432-0568
    Keywords: Key words Intrinsic laryngeal motoneurons ; Cholera toxin HRP ; Ultrastructure ; Swallowing ; Respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The laryngeal motoneurons innervating the cricothyroid muscle (CT) are located in the semicompact formation just ventral to the rostral part of the compact formation of the nucleus ambiguus. The motoneurons innervating the posterior cricoarytenoid muscle (PCA) are located in the loose formation. We retrogradely labeled the CT and the PCA motoneurons using cholera toxin subunit B-conjugated horseradish peroxidase, and determined the ultrastructure and synaptic organization of these neurons. The CT and the PCA motoneurons had the appearance of α-motoneurons, i.e., large, oval or polygonal cells containing well-developed organelles and a prominent spherical nucleus. Two kinds of neurons were recognized among the PCA motoneurons. The one (PCA-A) was significantly smaller than the other (PCA-B). The average number of axosomatic terminals in a section was significantly largest in the PCA-B (56.6), smaller in the PCA-A (36.0), and smallest in the CT (32.3) neurons. Most of the axosomatic terminals (64.7%) contained pleomorphic vesicles and made symmetric synaptic contacts (Gray’s type II) with the PCA-A neurons, while more than 60% contained round vesicles with asymmetric synaptic contacts (Gray’s type I) in the CT (69.5%) and the PCA-B (60.6%) neurons. A few terminals associated with subsurface cisterns were present on all laryngeal motoneurons. These results indicated that the CT motoneurons may receive mostly excitatory terminals, whereas the PCA muscle may be regulated by neurons having many inhibitory terminals, and neurons having many excitatory terminals.
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  • 17
    ISSN: 1432-069X
    Keywords: Key words p75 nerve growth factor receptor ; (p75 NGFr) ; Immunoreactivity ; Ultrastructure ; Prurigo nodularis ; Nerve fiber
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Prurigo nodularis is an inflammatory skin disease characterized by neurohyperplasia. Neurotrophins and their receptors play a critical role in nerve growth, differentiation, maturation and maintenance, including cutaneous nerve fiber growth and innervation. They may also be responsible for events related to the growth and differentiation control of keratinocytes. To explore the exact distribution of the p75 low-affinity nerve growth factor receptor (p75 NGFr) in the cutaneous nerve components, p75 NGFr immunofluorescence as well as ultrastructural immunohistochemical studies were performed on prurigo nodularis lesional skin and normal human skin samples. The immunofluorescence results revealed that nerve fibers and bundles were increased in number and size in lesional upper dermis with stronger p75 NGFr immunoreactivity than in the corresponding normal tissue. At the ultrastructural level, a lot of nerve fibers clustered together in the prurigo nodularis dermal tissue. The axons were enlarged and branched, but the axons themselves seldom showed any NGFr immunoreactivity. The Schwann cell bodies were extended and irregularly shaped, and tended to separate into many branches enveloping the axons. The Schwann cell membrane showed strong p75 NGFr immunoreactivity. The perineurium cells also revealed strong p75 NGFr immunoreactivity. The Schwann cells inside the perineurium were less p75 NGFr-immunoreactive than those outside the perineurium. The membrane of certain basal keratinocytes showed NGFr immunoreactivity as well. The present results indicate that overexpression of p75 NGFr in Schwann cells and perineurium cells could contribute to the neurohyperplasia in prurigo nodularis.
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  • 18
    ISSN: 1432-041X
    Keywords: Key words Imaginal disc ; Axonal trajectories ; Ultrastructure ; Chaoborus (Insecta ; Diptera)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  In one of his classical studies on insect metamorphosis, Weismann compared the imaginal anlagen of the ancestral phantom midge, Chaoborus, with those of advanced brachycerans. We have expanded his findings on the relationships between larval and imaginal organs using electron microscopy and cobalt backfilling of the antenna and leg anlagen and the axonal trajectories of corresponding larval sensilla. We show that both primordia are confluent with the larval antennae and ”leg” sensilla (an ancestral Keilin organ), respectively. These fully developed larval organs represent the distal tips of the imaginal anlagen rather than separate cell clusters. The axons of the larval antenna and leg sensilla project across the corresponding anlagen to their target neuromeres within the central nervous system (CNS). Within the discs, nerves composed of these larval axons, developing afferent fibres and efferences ascending from the CNS are found. Both the structure of the primordia and the axonal trajectories thus relate the situation found in advanced brachycerans with that seen in more ancestral insects. In addition, the larval antennae, legs, wings and even the eyes possess very similar afferent pioneer trajectories supporting the idea that the described pattern is generally used in the ontogeny of sensory systems.
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  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Sexual plant reproduction 12 (1999), S. 99-109 
    ISSN: 1432-2145
    Keywords: Key words Arabidopsis thaliana ; Megasporogenesis ; Meiosis ; Ultrastructure ; Cellular polarity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  In this study, megasporogenesis of the plant model Arabidopsis thaliana was investigated by electron microscopy for the first time. The data described here could constitute a reference for future investigations of Arabidopsis mutants. During the beginning of meiosis the megaspore mother cell shows a polarity created by unequal distribution of organelles in the cytoplasm. Plastids accumulate in the chalazal region and long parallel saccules of endoplasmic reticulum, small vacuoles and some dictyosomes are found in the micropylar region. Plasmodesmata are abundant in the chalazal cell wall. The nucleus is almost centrally localized and contains a prominent excentric nucleolus and numerous typical synaptonemal complexes. After the second division of meiosis the four megaspores are separated by thin cell walls crossed by numerous plasmodesmata and do not show significant cellular organization. The young functional megaspore is characterized by a large nucleus and a large granular nucleolus. The cytoplasm is very electron dense due to the abundance of free ribosomes and contains the following randomly distributed organelles: mitochondria, a few short saccules of endoplasmic reticulum, dictyosomes and undifferentiated plastids. However, there is no apparent polarity, except for the distribution of some small vacuoles which are more abundant in the micropylar region of the cell. The degenerating megaspores are extremely electron dense and do not show any substructure.
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  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 124 (1999), S. 89-99 
    ISSN: 1432-1106
    Keywords: Key words Microglial culture ; Brain macrophages ; Isolectin ; Ultrastructure ; Intracellular pathway
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The present study examined the lectin labeling of diverse morphological forms of microglia in culture. Similar to amoeboid microglial cells in vivo, polymorphic microglia showed lectin labeling at their plasma membranes, as well as in a few cytoplasmic vesicles and vacuoles. This labeling pattern was observed in cultured microglia incubated with isolectin at 4°C for 30 min. Five minutes after the temperature was raised to 37°C, the surface lectin receptors appeared to be internalized, as shown by the occurrence of many subsurface lectin-labeled vesicles, vacuoles and tubule-like structures. With longer incubation (up to 1–2 h at 37°C), many lysosomes and a few trans-Golgi saccules and associated lysosome-like structures became labeled. Concomitant with these changes was a reduction of lectin labeling at the plasma, with labeling having vanished in most of the cells after 1–2 h of incubation. By 24 h, only a few cells retained surface lectin labeling. It appears, therefore, that irrespective of morphology, lectin labeling (including its intracellular pathway) of microglia in culture parallels that of amoeboid microglia in vivo. This would offer a useful model for the study of lectin turnover in microglia and help to explain the roles of such receptors in microglial differentiation and function.
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  • 21
    ISSN: 1432-072X
    Keywords: Key wordsClostridium xylanolyticum ; Cinnamic acid ; Esterase ; Lignocellulose ; Sporogenesis ; Ultrastructure ; Cell envelope
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Microorganisms that hydrolyse the ester linkages between phenolic acids and polysaccharides in plant cell walls are potential sources of enzymes for the degradation of lignocellulosic waste. An anaerobic, mesophilic, spore-forming, xylanolytic bacterium with high hydroxy cinnamic acid esterase activity was isolated from the gut of the grass-eating termite Tumilitermes pastinator. The bacterium was motile and rod-shaped, stained gram-positive, had an eight-layered cell envelope, and formed endospores. Phylogenetic analysis based on 16S rRNA indicated that the bacterium is closely related to Clostridium xylanolyticum and is grouped with polysaccharolytic strains of clostridia. A wide range of carbohydrates were fermented, and growth was stimulated by either xylan or cellobiose as substrates. The bacterium hydrolysed and then hydrogenated the hydroxy cinnamic acids (ferulic and p-coumaric acids), which are esterified to arabinoxylan in plant cell walls. Three cytoplasmic enzymes with hydroxy cinnamic acid esterase activity were identified using non-denaturing gel electrophoresis. This bacterium possesses an unusual multilayered cell envelope in which both leaflets of the cytoplasmic membrane, the peptidoglycan layer and the S layer are clearly discernible. The fate of all these components was easily followed throughout the endospore formation process. The peptidoglycan component persisted during the entire morphogenesis. It was seen to enter the septum and to pass with the engulfing membranes to surround the prespore. It eventually expanded to form the cortex, verification for the peptidoglycan origin of the cortex. Sporogenic vesicles, which are derived from the cell wall peptidoglycan, were associated with the engulfment process. Spore coat fragments appeared early, in stage II, though spore coat formation was not complete until after cortex formation.
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  • 22
    ISSN: 1432-0878
    Keywords: Key words Chondrocyte ; Synoviocyte ; Co-culture ; Proliferation ; Lipid peroxidation ; Cytotoxicity ; Ultrastructure ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Objective: A new co-culture system of rat articular chondrocytes and synoviocytes (HIG-82; cell line) was incubated with phorbol myristate acetate (PMA), H2O2 or a combination of Fe2+ and ascorbic acid to simulate inflammation-like radical attacks in articular joints. Methods: Chondrocytes were characterized by immunocytochemistry against collagen type II, transmission electron (TEM) and light microscopy. Lipid peroxidation was investigated by measuring thiobarbituric-acid-reactive material in the supernatants, cytotoxicity by determining release of lactate dehydrogenase and proliferation by measuring [3H]thymidine incorporation, culture protein and DNA. Results: PMA or Fe2+ and ascorbic acid induced lipid peroxidation in chondrocytes and synoviocytes that was decreased significantly in co-cultures. PMA and H2O2 dose dependently induced release of lactate dehydrogenase in chondrocytes, which was lowered in co-cultures or in previously co-cultured chondrocytes to a nearly basal level. In contrast, conditioned media of synoviocyte cultures showed no lowering effect on the radical-induced toxicity. Protection against H2O2-induced damage of cellular membranes by co-culturing was also shown by TEM. Synoviocytes released chondrocyte-stimulating growth factors spontaneously without previous interaction. Conclusion: Chondrocytes establish protective mechanisms against reactive oxygen species via an interaction with synoviocytes. Our co-culture model presents a possible way to study mechanisms of inflammation in articular joints under defined conditions.
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  • 23
    ISSN: 1432-0878
    Keywords: Key words Chloride cells (mitochondria-rich cells) ; Teleost larvae ; Osmoregulation ; Immunohistochemistry ; Quantification ; Ultrastructure ; Oreochromis mossambicus (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Integumental and branchial chloride cells of tilapia larvae (Oreochromis mossambicus) were studied at the light-microscopical and ultrastructural level. Total numbers and distribution of chloride cells were quantified after immunostaining of cross sections of the entire larvae with an antibody against the α-subunit of Na+/K+-ATPase. The majority (66%) of Na+/K+-ATPase-immunoreactive (ir) cells, i.e. chloride cells, of freshwater tilapia larvae were located extrabranchially up to 48 h after hatching. Five days after hatching, the majority (80%) of chloride cells were found in the buccal cavity. Transfer of 24-h-old larvae to 20% sea water speeded up this process; 24 h after transfer (i.e. 48 h after hatching), the majority (59%) of chloride cells were located in the buccal cavity. The branchial chloride cell population of 24-h- and 120-h-old larvae consisted of immature, mature, apoptotic and necrotic chloride cells. However, relatively more immature chloride cells were observed in freshwater larvae (42–63%) than in (previously studied) freshwater adults (21%), illustrating the developmental state of the gills. After transfer to sea water, the incidence of degenerative chloride cells did not change. Furthermore, the incidence of immature cells had decreased and a new subtype of chloride cells, the ”mitochondria-poor” cells, appeared more frequently. These mitochondria-poor chloride cells were characterised by an abundant tubular system and relatively few mitochondria, which were aligned at the border or concentrated in one part of the cytoplasm. Most of these cells did not contact the water. The function of their enhanced appearance after seawater transfer is unknown.
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  • 24
    ISSN: 1432-0878
    Keywords: Key words Mechanoreceptors ; Synaptic proteins ; Histochemistry ; Ultrastructure ; Slit sensilla ; Hair sensilla ; Cupiennius salei (Chelicerata)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Indirect immunocytochemical tests were used at the light- and electron-microscopic levels to investigate peripheral chemical synapses in identified sensory neurons of two types of cuticular mechanosensors in the spider Cupiennius salei Keys.: (1) in the lyriform slit-sense organ VS-3 (comprising 7–8 cuticular slits, each innervated by 2 bipolar sensory neurons) and (2) in tactile hair sensilla (each supplied with 3 bipolar sensory cells). All these neurons are mechanosensitive. Application of a monoclonal antibody against Drosophila synapsin revealed clear punctate immunofluorescence in whole-mount preparations of both mechanoreceptor types. The size and overall distribution of immunoreactive puncta suggested that these were labeled presynaptic sites. Immunofluorescent puncta were 0.5–6.8 μm long and located 0.5–6.6 μm apart from each other. They were concentrated at the initial axon segments of the sensory neurons, while the somata and the dendritic regions showed fewer puncta. Western blot analysis with the same synapsin antibody against samples of spider sensory hypodermis and against samples from the central nervous system revealed a characteristic doublet band at 72 kDa and 75 kDa, corresponding to the apparent molecular mass of synapsin in Drosophila and in mammals. Conventional transmissionelectron-microscopic staining demonstrated that numerous chemical synapses (with at least 2 vesicle types) were present at these mechanosensory neurons and their surrounding glial sheath. The distribution of these synapses corresponded to our immunofluorescence results.Ultrastructural examination of anti-synapsin-stained neurons confirmed that reaction product was associated with synaptic vesicles. We assume that the peripheral synaptic contacts originate from efferents that could exert a complex modulatory influence on mechanosensory activity.
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  • 25
    ISSN: 1432-0878
    Keywords: Key words Teleost fish ; Puberty ; Testes ; Sex steroids ; Ultrastructure ; Steroidogenesis ; Clarias gariepinus (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The present report focuses on the mechanism(s) involved in the steroid-induced decrease of androgen production in immature African catfish testes that was observed in previous studies. Juvenile animals were implanted with Silastic pellets containing different 11-oxygenated androgens (11-ketotestosterone, KT; 11β- hydroxyandrostenedione, OHA; 11-ketoandrostenedione, KA), testosterone (T) or estradiol-17β (E2). Control groups received steroid-free pellets. Two weeks later, testis tissue fragments were either incubated with increasing concentrations of catfish luteinizing hormone (LH), or incubated with [3H]-pregnenolone ([3H]-P5) or [3H]-androstenedione ([3H]-A). Tissue fragments were also prepared for the quantitative assessment of Leydig cell morphology. Most of the parameters studied were not affected significantly by implantation of E2. Implantation of all androgens inhibited both the basal and the LH-stimulated androgen secretory capacity in vitro. This was associated with a reduced size of the Leydig cells and loss of half of their mitochondria. The studies on the metabolism of tritiated steroid hormones indicated that steroidogenic steps prior to 11β-hydroxylation, probably C17–20 lyase activity, were affected by all androgens. Although the effects of 11-oxygenated androgens and T on Leydig cells were mostly similar, previous work showed that only the 11-oxygenated androgens stimulated spermatogenesis, suggesting that distinct mechanisms of action are used by 11-oxygenated androgens and T. These mechanisms, however, seem to merge on the same target(s) to impair Leydig cell androgen production. Such a negative feedback mechanism may be of relevance in the context of the decline in androgen secretion per milligram testis tissue that accompanies the first wave of spermatogenesis in pubertal African catfish.
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  • 26
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 295 (1999), S. 151-158 
    ISSN: 1432-0878
    Keywords: Key words Class II MHC-positive cells ; Human leukocyte antigen-DR ; Dental pulp ; Dendritic cells ; Macrophages ; Ultrastructure ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The distribution and ultrastructure of class II major histocompatibility complex (MHC)-positive cells were investigated in human dental pulp, employing immunohistochemistry using an anti-human leukocyte antigen (HLA)-DR-monoclonal antibody. HLA-DR-immunopositive cells, appearing spindle-like or dendritic in profile, were densely distributed throughout the dental pulp. Under the electron microscope, these cells exhibited various sizes of vesicles containing clear or opaque contents, multivesicular bodies and characteristic fine tubulovesicular structures in their cytoplasm. Some reactive cells possessed coated pits and vesicles including electron-dense materials, indicating an active endocytosis. At the periphery of the pulp tissue, the HLA-DR-immunopositive cells were predominantly situated in the subodontoblastic layer, with some located in the odontoblast layer and/or predentin and extending their cytoplasmic processes into the dentinal tubules. Cell processes of these cells occasionally made contact with several odontoblast processes in the same way as the nerve fibers in the predentin. These cells never contained the typical phagosomes frequently observed in the HLA-DR-immunoreactive macrophages in the subodontoblastic layer and the pulp core. The results suggest that the HLA-DR-immunopositive cells in the odontoblast layer and/or predentin have some regulatory function on the odontoblasts under physiological conditions, in addition to their involvement in the initial defense reaction after tooth injury.
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  • 27
    ISSN: 1432-0878
    Keywords: Key words Neuromelanin ; Neuron ; Peroxidase ; Oxygen metabolism ; High-definition light microscopy ; Electron microscopy ; Ultrastructure ; Cytochemistry ; Substantia nigra ; Lumbricusterrestris (Annelida)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Histochemical examination of 1-μm tissue sections from the dorsal nerve plexus of the earthworm, Lumbricus terrestris, reveals multiple brown intraneuronal granules. These granules contain material morphologically and histochemically consistent with neuromelanin. When viewed with transmission electron microscopy, these were seen as single membrane-enclosed biphasic granules with diameters of 370–730 nm. Exposure of L. terrestris to high-level environmental oxygen resulted in an increase in the number of neuromelanin-like pigment granules within the neurons of the circular muscle layer. As measured by ortho-phenylenediamine hydrochloride, the endogenous peroxidase activity of extracts from worms incubated in high-level environmental oxygen was 51% more than controls. The endogenous peroxidase activity was localized in situ with 3,3-diaminobenzidine (DAB) and was found to increase in and around the neuromelanin-like pigment-containing neurons within the circular muscle layer. These studies suggest that the nerve net of L. terrestris may serve as a model to study the role of neuromelanin production in oxidative stress and its relationship to endogenous peroxidases.
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  • 28
    ISSN: 1432-0878
    Keywords: Key words Melanin-concentrating hormone neurons ; Lateral hypothalamic slice culture ; Immunocytochemistry ; Ultrastructure ; In situ hybridization ; Competitive RT-PCR ; Leptin assay ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Hypothalamic slices containing the lateral hypothalamic area (LHA) were prepared from 6- to 8-day-old rats and maintained in stationary culture for up to 35 days in order to analyse how well the melanin-concentrating hormone (MCH) neurons survived. As previously reported for other brain areas, this method yielded a long-term well-preserved organotypic organization. Light- and electron-microscopic investigations showed that differentiation continued and that synaptic contacts developed in vitro. After a period of elimination of damaged cells and fibres, most of the remaining neurons and glial cells retained a normal morphology throughout the culture period. MCH neurons, in particular, survived well as attested by the strong immunocytochemical and in situ hybridization signals still observed after several weeks. In a comparison with the day of explantation, competitive reverse transcription/polymerase chain reaction demonstrated the remarkable stability of the level of MCH mRNA at least until the 20th day in culture; after 30 days, the clear decrease in this level seemed to be correlated with a loss of MCH neurons, rather than with a decrease in MCH expression. After 10 days of culture, the incubation of slices in the presence of the hormone leptin (50 ng/ml) resulted in a strong decrease of MCH gene expression, suggesting that MCH neurons retained their physiological properties. Thus, the LHA slice stationary culture, especially between one and three weeks (i.e. after tissue stabilization and before extensive cell loss), appears to be a suitable method for physiological and pharmacological studies of these neurons.
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  • 29
    ISSN: 1432-0878
    Keywords: Key words ECL cells ; Gastrin ; Reserpine ; Organelles ; Ultrastructure ; Rat (Sprague-Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The histamine-storing ECL cells in the stomach play a key role in the control of acid secretion. They contain granules, secretory vesicles and microvesicles, and sustained gastrin stimulation results in the additional formation of vacuoles and lipofuscin bodies. The cells are rich in the vesicle monoamine transporter type-2 (VMAT-2), which can be inhibited by reserpine. The present study examines the effect of reserpine on ECL-cell ultrastructure and histamine compartmentalization. Rats received reserpine and/or gastrin. Reserpine was given twice by the intraperitoneal route (25 mg/kg once daily). Gastrin-17 was given by subcutaneous infusion (5 nmol/kg/h), starting at the time of the first reserpine injection and continuing for 4 days when the rats were killed. At this stage, histamine in the oxyntic mucosa was unaffected by reserpine but elevated by gastrin. Immunocytochemical analysis (confocal microscopy) showed ECL-cell histamine in control and gastrin-treated rats to be localized in cytoplasmic organelles (e.g., secretory vesicles). After treatment with reserpine alone or reserpine+gastrin, ECL-cell histamine occurred mainly in the cytosol. Planimetric analysis (electron microscopy) of ECL cells showed reserpine to increase the number, size and volume density of the granules and to reduce the size and volume density of the secretory vesicles. Gastrin reduced the number and volume density of granules and secretory vesicles, increased the number and volume density of microvesicles and caused vacuoles and lipofuscin bodies to appear. Reserpine+gastrin increased the number, volume density and size of the granules. Reserpine prevented the effects of gastrin on secretory vesicles, vacuoles and microvesicles, but did not prevent the development of lipofuscin. Our findings are in line with the views: (1) that preformed cytosolic histamine is taken up by granules/secretory vesicles via VMAT-2, that histamine is instrumental in the transformation of granules into secretory vesicles and in their consequent enlargement and (2) that vacuoles are formed by the fusion of large secretory vesicles.
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  • 30
    ISSN: 1615-6102
    Keywords: Cumulus oophorus ; Ovarian follicle ; Fertilization ; Ultrastructure ; Immunocytochemistry ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The fine structure of the human cumulus oophorus has been reviewed on the basis of scanning and transmission electron microscopic observations as well as of immunofluorescence data. Tissues sampled from preovulatory ovarian follicles and cumulus-enclosed oocytes and fertilized eggs (collected from the oviduct or obtained during in vitro fertilization procedures) have been evaluated from a microtopographic and morphodynamic point of view in order to better clarify the possible role of this population of cells. In particular, the following aspects have been studied and discussed: the presence of multiple close contacts (modulated by the interposition of the zona pellucida) between the oocyte surface and the long microvillous evaginations projecting from the inner aspect of corona cells surface (through these structures the intraovarian cumulus oophorus may control oocyte growth and metabolism up until the time of ovulation); the occurrence of different subpopulations of cells (steroid-synthetic cells, cells producing adhesive proteins, leukocytes, macrophages) in the postovulatory, extraovarian cumulus oophorus surrounding oocytes, zygotes and early developing embryos. All these elements found in the cumulus mass may positively act, through their paracrine activities, on the chemical composition of the microenvironment in which fertilization occurs.
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  • 31
    ISSN: 1615-6102
    Keywords: Plasmalemmic cord ; Pollen grain ; Ultrastructure ; Magnolia ×soulangeana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary InMagnolia ×soulangeana pollen grains the generative cell (GC) does not become totally free within the vegetative cell (VC), at least until the pollen tube emergence. Due to a deviation in its detachment process from the sporoderm, the opposing ends of the VC plasmalemma do not fuse themselves when the GC moves away from the intine. Consequently, the interplasmalemmic space surrounding the GC does not become isolated but rather maintains continuity with the sporoderm through a complex formation that we have called plasmalemmic cord. The real existence of this formation was confirmed through serial sectioning showing the plasmalemmic cord to consist of the VC plasmalemma. In its initial portion it is occupied by a reasonably accentuated wall ingrowth of the inner layer of the intine (intine 3). In the remainder portion, neither of the cytochemical tests used in this work have revealed the presence of a significant amount of wall material. However, ultrathin sections of samples processed either chemically or by cryofixation showed the existence of an intricate system of tubules and vesicles, some of which are evaginations of the VC plasmalemma. The hypothesis that the plasmalemmic cord may have a role in the complex interactions between the two pollen cells is discussed.
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  • 32
    ISSN: 1615-6102
    Keywords: Anatomy ; Floral nectary ; Modified stomata ; Phloem ; Pisum sativum ; Stereology ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The floral nectary ofPisum sativum L. is situated on the receptacle at the base of the gynoecium. The gland receives phloem alone which departed the vascular bundles supplying the staminal column. Throughout the nectary, only the companion cells of the phloem exhibited wall ingrowths typical of transfer cells. Modified stomata on the nectary surface served as exits for nectar, but stomatal pores developed well before the commencement of secretion. Furthermore, stomatal pores on the nectary usually closed by occlusion, not by guard-cell movements. Pore occlusion was detected most frequently in post-secretory and secretory glands, and less commonly in pre-secretory nectaries. A quantitative stereological study revealed few changes in nectary fine structure between buds, flowers secreting nectar, and post-secretory flowers. Dissolution of abundant starch grains in plastids of subepidermal secretory cells when secretion commenced suggests that starch is a precursor of nectar carbohydrate production. Throughout nectary development, mitochondria were consistently the most plentiful organelle in both epidermal and subepidermal cells, and in addition to the relative paucity of dictyosomes, endoplasmic reticulum, and their associated vesicles, the evidence suggests that floral nectar secretion inP. sativum is an energy-requiring (eccrine) process, rather that granulocrine.
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  • 33
    ISSN: 1615-2573
    Keywords: Endomyocardial biopsy ; Dilated cardiomyopathy ; Children ; Ultrastructure ; Basal lamina layering of capillary
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We analyzed the electron-microscopic features of endomyocardial biopsy from pediatric patients with dilated cardiomyopathy (DCM). The specimens examined were taken from the right ventricle of ten patients aged from 2 to 15 years (mean 9.7 years). Biopsy specimens from eight patients with congenital heart disease (tetralogy of Fallot), aged from 3 to 12 (mean 7.3 years), and ten adult patients with DCM, aged from 32 to 60 (mean 45 years), were also examined. Patients considered to have endocardial fibroelastosis, arrhythmogenic right ventricular cardiomyopathy, specific cardiomyopathy, or coronary heart disease were excluded from this study. Specimens from pediatric patients with DCM showed various degrees of ultrastructural abnormalities of myocytes, including myofibrillar fragmentation, mitochondrial abnormalities, and intracellular edema. The ultrastructurally determined contractility failure index based on the severity of myocardial degeneration at the electronmicroscopic level was 4.9 ± 1.1. This value was significantly higher than that in patients with tetralogy of Fallot (0.9 ± 0.6,P 〈 0.001) but was not significantly different from that in adult patients with DCM (6.1 ± 2.6). The index of pediatric patients with DCM who died within 3 years was high (6.0 ± 0.8). Basal lamina layering of a capillary (BLL) in the myocardium was revealed in 1 of the 10 (10%) pediatric patients with DCM and in 6 of the 10 (60%) adult patients with DCM (P 〈 0.05). No BLL was noted in the patients with tetralogy of Fallot. These findings may be related to the pathogenesis of DCM in children and adults.
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  • 34
    ISSN: 1615-6102
    Keywords: Endosymbiont ; Mycetocyte ; Mycetome ; Oocyte ; Transovarial transmission ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary All anoplurans live symbiotically with prokaryotic microorganisms hosted in specialized cells, termed mycetocytes. In nymphs and males mycetocytes are distributed between midgut epithelial cells. In females, besides the midgut, mycetocytes are found in the reproductive organs where they are located at the base of ovarioles in contact with lateral oviducts. The mycetocyte-associated symbionts are transmitted from one generation to the next transovarially. Here, the results of histological and ultrastructural studies on the distribution and transmission of symbiotic microorganisms within the ovaries of the anopluranHaematopinus suis are presented. Interestingly, during advanced oogenesis (i.e., choriogenesis) of this species all symbionts are localized extracellularly and form a tight mass located at the posterior pole of the oocyte just below the hydropyle. In insects studied so far, such localization of transovarially transmitted microorganisms has been reported only in the closely related speciesHaematopinus eurysternus.
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  • 35
    ISSN: 1432-136X
    Keywords: Key words Freeze tolerance ; Sciatic nerve ; Cryoinjury ; Dehydration ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We investigated function and ultrastructure of sciatic nerves isolated from wood frogs (Rana sylvatica) endemic to the Northwest Territories, Canada, following freezing at −2.5 °C, −5.0 °C, or −7.5 °C. All frogs frozen at −2.5 °C, and most frogs (71%) frozen at −5.0 °C, recovered within 14 h after thawing began; however, frogs did not survive exposure to −7.5 °C. Sciatic nerves isolated from frogs frozen at −7.5 °C were refractory to electrical stimulation, whereas those obtained from frogs surviving exposure to −2.5 °C or −5.0 °C generally exhibited normal characteristics of compound action potentials. Frogs responded to freezing by mobilizing hepatic glycogen reserves to synthesize the cryoprotectant glucose, which increased 20-fold in the liver and 40-fold in the blood. Ultrastructural analyses of nerves harvested from frogs in each treatment group revealed that freezing at −2.5 °C or −5.0 °C had little or no effect on tissue and cellular organization, but that (lethal) exposure to −7.5 °C resulted in marked shrinkage of the axon, degeneration of mitochondria within the axoplasm, and extensive delamination of myelin sheaths of the surrounding Schwann cells.
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  • 36
    Electronic Resource
    Electronic Resource
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    Parasitology research 85 (1999), S. 999-1006 
    ISSN: 1432-1955
    Keywords: Key wordsEchinococcus granulosus ; Praziquantel ; Metacestode ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The efficacy of praziquantel against the metacestode of Echinococcus granulosus was studied by means of in vitro incubations or in vivo experiments. The results of in vitro incubations indicated that the effectiveness of praziquantel was higher when the parasite material comprised cysts from cyst masses than in the case of intact cysts that retained their adventitial layer. Ultrastructural alterations in the germinal layer of collapsed cysts incubated in vitro were detected. The results obtained in mice after 4 months of treatment demonstrated no significant difference between the control and treated groups with regard to the number and wet weight of developed cysts. However, ultrastructural alterations were detected in the cyst tissue that were similar to those described in the in vitro experiment. In contrast, the effect of chemoprophylaxis on the number and the wet weight of developed cysts was extremely significant as compared with the control value, the efficacy being 99.41% and 98.32%, respectively. Moreover, ultrastructural observations of the cyst tissue revealed loss of its integrity, and no intact cyton was observed in the germinal layer of the developed cyst.
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  • 37
    ISSN: 1432-1955
    Keywords: Key words Monogenea ; Capsalidae ; Benedenia rohdei ; B. lutjani ; Ectoparasites ; Lutjanus carponotatus ; Glands ; Ultrastructure ; Adhesion ; Attachment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The anterior adhesive areas of Benedenia rohdei from the gills and B. lutjani from the pelvic fins of Lutjanuscarponotatus at Heron Island, Australia, were studied using scanning and transmission electron microscopy. All specimens were fixed when detached from host tissue. Both monogenean species have two disc-like anteroventral attachment organs, each of which has an anterolateral adhesive area divided into three adjacent zones by tegument from the ventral surface of the attachment organ. A rod-shaped secretion and a smaller, roughly spherical secretion are associated with the anterior adhesive areas in both species; a third type of secretion occurs anteriorly but outside these adhesive areas. The electron-dense spherical secretory bodies released onto the anterior adhesive zones in these Benedenia spp. are of a single type and differ ultrastructurally from those previously reported in monogeneans living on teleost hosts. A correlation, therefore, between secretion morphology and host type is not supported. No relationship was found between parasite microhabitat and secretion morphology.
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  • 38
    ISSN: 1861-387X
    Keywords: Meningioma ; Intranuclear inclusion ; Immunohistochemistry ; Ultrastructure ; Intermediate filament
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We describe a case of meningothelial meningioma with a large number of intranuclear inclusions. Morphologically, these are divided into cytoplasmic inclusions and nuclear vacuoles. The cytoplasmic inclusion has a limiting membrane with cell organelles and filaments. Inclusions of this type are generally eosinophilic, like the cytoplasm. However, there are many inclusions that are more eosinophilic than the cytoplasm or that have a ground-glass appearance. Some of them may contain fine or coarse granules. On the other hand, the nuclear vacuole lacks a limiting membrane and appears empty. In most of the inclusions of this type, there is a faintly basophilic substance in the margin. Generally, the cytoplasmic inclusions are as immunopositive as cytoplasm with vimentin, but some of these cytoplasmic inclusions are more reactive. Under the electron microscope, abnormal aggregation of intermediate filaments is recognized in the cytoplasmic inclusions. It is considered that a strong reaction of cytoplasmic inclusions with vimentin immunostaining is due to abnormal aggregation of intermediate filaments. The present study distinctly demonstrates abnormal localization of intermediate filaments in the cytoplasmic inclusions, and it is suggested that the cytoskeleton participates in the evolution of the cytoplasmic inclusions.
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  • 39
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 10 (1972), S. 38-48 
    ISSN: 1432-0827
    Keywords: Bivalve ; Molluse ; Shell ; Carbonates ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé La technique du bombardement à l'aide d'ion d'argon est utilisée pour réduire l'épaisseur de la coquille de carbonate de calcium des bivalvesMytilus etMercenaria pour examen au microscope électronique par transmission et en diffraction électronique; une comparaison est réalisée à l'aide de répliques simples, servant de témoins. Les résultats obtenus confirment les études antérieures de répliques et de microscopie par balayage. De plus, une structure “aérée” est mise en évidence dans la coquille des aragonites, et surtout dans le nacre deMytilus. Cette structure est interprêtée comme un artefact induit par la chaleur, formé par l'inclusion d'eau et de matériel organique, interprétation qui concorde avec les études chimiques et de microscopie électronique.
    Abstract: Zusammenfassung Die Beschießung mit Argonionen wurde angewendet, um die Dicke von Calciumcarbonat-Schalen der zweischaligen MuschelnMytilus undMercenaria zu reduzieren. Diese Technik erlaubte die Ausführung von Transmissions-Elektronenmikroskopie und Elektronendiffraktion, wobei gleiche Proben nach einer bereits bestehenden Methode vorbereitet und als Kontrollen herangezogen wurden. Es wurden zusätzliche Resultate zu den Muschelstruktur-studien erhalten, welche früher publizierte Arbeiten unterstützen, die mit der Abklatschmethode und der Raster-Elektronenmikroskopie ausgeführt worden waren. Zusätzlich wurde eine „schaumartige” Struktur der Muschelaragoniten, besonders im Perlmutter vonMytilus, beobachtet. Da es sich um ein durch Hitze verursachtes Artefakt handelt, wird diese Struktur als Einschlüsse von Wasser und organischem Material interpretiert, was den Befunden von verschiedenen veröffentlichten chemischen und elektronenmikroskopischen Arbeiten entspricht.
    Notes: Abstract Use is made of the argon ion-bombardment technique to reduce the thickness of calcium carbonate shells of the bivalvesMytilus andMercenaria for transmission electron microscopy and electron diffraction, with comparison of single-stage replicas of similar specimens serving as controls. As an additional approach to shell structure studies, it gives results which support earlier published work with both replicas and scanning microscopy. In addition, a “frothy” structure is detected in the shell aragonites, especially inMytilus nacre. As a heat-induced artifact, it is interpreted as representing trapped water and organic material inclusions, an interpretation consistent with several published chemical and electron microscope studies.
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  • 40
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    Calcified tissue international 10 (1972), S. 216-222 
    ISSN: 1432-0827
    Keywords: Ultrastructure ; Callus ; Osteoclast ; Endocytosis ; Lysosomes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé La bordure en brosse des ostéoclastes de cals de fractures de rats présente des plissements complexes de la membrane cytoplasmique formant des canaux étroits. L'absorption d'un produit exogène opaque aux électrons (des macromolécules de dioxyde de thorium) s'effectue par l'intermédiaire de ces canaux, par un «courant» membranaire. Les contenus des canaux sont transférés à des lysosomes («granules spécifiques»), situés sous la bordure en brosse. Dans des «régions de transition», adjacentes à cette dernière, l'absorption de dioxyde de thorium se fait par «vésiculation membranaire» (endocytose classique).
    Abstract: Zusammenfassung Der gekrauste Rand der Osteoklasten im Frakturcallus von Ratten besteht aus komplexen Einstülpungen der Plasmamembran, die enge Kanälchen bildet. Die Absorption einer exogenen, elektronisch dichten Verbindung, Thoriumdioxyd, erfolgt durch diese Kanäle, offenbar durch einen „Membranfluß”. Der Inhalt der Kanäle wird zu den Lysosomen („spezifische Granula”) geführt, welche unter dem gekrausten Rand liegen. In „Übergangsgebieten”, welche sich neben dem gekrausten Rand befinden, scheint die Aufnahme der Thoriumdioxydpartikel durch „Bläschenbildung in der Membran” (konventionelle Endocytose) stattzufinden.
    Notes: Abstract The ruffled border of osteoclasts in the fracture callus of rat consists of complex infoldings of the plasma membrane forming narrow channels. Absorption of an exogenous, electron-dense compound, thorium dioxide, has been shown to take place via these channels, apparently through “membrane flow”. The contents of the channels are transferred to lysosomes (“specific granules”) located subjacent to the ruffled border. In “transitional regions” adjacent to the ruffled border, uptake of thorium dioxide particles appeared to occur through “membrane vesiculation” (conventional endocytosis).
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  • 41
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    Calcified tissue international 9 (1972), S. 296-309 
    ISSN: 1432-0827
    Keywords: Osteoclasts ; Enzyme ; Parathyroid ; Microdissection ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Une nouvelle méthode d'isolement d'ostéoclastes est mise au point pour des analyses biochimiques et de microscopie électronique. Pour isoler les cellules par microdissection, des empreintes d'os métaphysaire sont utilisées. Cette méthode, supérieure aux coupes d'os, permet une meilleure préservation cytologique et enzymatique et permet d'obtenir des cellules totales plus faciles à manipuler, avec des résultats plus reproductibles. Par analyse planimètrique de cellules isolées, colorées histochimiquement, il apparait que les ostéoclastes constituent plus de 90% de la masse de l'échantillon. Les concentrations de la phosphatase acide et de certaines enzymes, liées au nucléotide pyridinique, entrant dans le métabolisme de l'acide citrique, sont déterminées dans des échantillons d'ostéoclastes, pesant de 0,2 à 2,0 μg, isolés à partir de rats normaux et parathyroidectomisés. L'activité en aconitase, mesurée en direction de la transformation de citrate en isocitrate, est de 0,5–0,8 M/Kd/H, la plus faible des activités étudiées. Les activités en GDH et NADP-ICDH sont 5 à 10 fois supérieures que celle de l'aconitase, mais seulement un dixième à un tiers de celle de la phosphatase acide, de la déshydrogénase lactique ou malique.
    Abstract: Zusammenfassung Es wird eine neue Technik beschrieben, welche die Isolierung von Osteoklasten für biochemische und elektronenmikroskopische Untersuchungen ermöglicht. Als Ausgangsmaterial zur Zellisolierung wurden Abstriche von Metaphysenknochen benützt. Die Verwendung von Abstrichen bietet gegenüber Knochenschnitten wichtige Vorteile, wie z.B. eine bessere Erhaltung der cytologischen und enzymatischen Eigenschaften sowie die Gewinnung von unverletzten Zellen, welche leichter verarbeitet werden können und besser reproduzierbare Daten ergeben. Durch planimetrische Analyse der histochemisch gefärbten Ausstriche von isolierten Zellen konnte nachgewiesen werden, daß die Osteoklasten über 90% des gesamten Probenmaterials ausmachen. Die Mengen verschiedener Enzyme, welche an Pyridinnukleotid gebunden und am Citronensäuremetabolismus beteiligt sind, sowie der sauren Phosphatase wurden in Osteoklastenproben bestimmt, welche ein Gewicht von 0,2–2,0 μg hatten und aus Knochen von normalen und mit Parathyroidextrakten behandelten Ratten isoliert worden waren. Die Aktivität der Aconitase, welche in der Richtung von Citrat zu Isocitrat gemessen wurde, war mit 0,5–0,8 M/Kd/H die niedrigste aller untersuchten Aktivitäten. Die Aktivitäten der GDH und der NADP-ICDH waren 5–10mal höher als jene der Aconitase, entsprachen jedoch nur einem Zehntel bis einem Drittel derjenigen der sauren Phosphatase, der Laktat- oder der Malatdehydrogenase.
    Notes: Abstract A new method is described by which osteoclasts can be isolated for biochemical and electron microscopic analyses. As a source of cells for isolation by microdissection, imprints of metaphyseal bone were used. The use of imprints provides important advantages over bone sections, including a higher degree of cytologic and enzymatic preservation, and the delivery of whole cells which are more readily manipulated and which yield data that are more readily reproduced. By planimetric analysis of the histochemically-stained isolated cell samples, it was shown that osteoclasts represent over 90% of the sample mass. The levels of several of the pyridine nucleotide-linked enzymes involved in citric acid metabolism, as well as acid phosphatase, were determined in osteoclast samples weighing 0.2 to 2.0 μg isolated from normal and parathyroid-treated rats. Aconitase activity measured in the direction of citrate to isocitrate was 0.5–0.8 M/Kd/H, the lowest of the activities studied. The activities of GDH and NADP-ICDH were 5 to 10 times higher than that of aconitase but only a tenth to a third that of acid phosphatase, lactic or malic dehydrogenase.
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  • 42
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    Research in experimental medicine 159 (1972), S. 87-98 
    ISSN: 1433-8580
    Keywords: Ultrastructure ; Small lymphocytes ; Throracic duct lymph ; Man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die charakteristische Feinstruktur der durch Drainage des Ductus thoracicus des Menschen gewonnenen Lymphocyten wurde beschrieben, ihre Größe und Kern-Plasma-Relation durch planimetrische Verfahren ermittelt. Zwei morphologisch unterschiedliche Formen kleiner Lymphocyten konnten beschrieben werden: Zellen, die durch einen chromatinarmen Kern und relativ lockeres Cytoplasma gekennzeichnet sind, das zahlreiche Zellorganellen (Golgifeld, Centriolen, Mitochondrien und freie diffus verteilte Ribosomen) einschließt, sowie Zellen mit chromatinreichen Kern und dichtem Cytoplasma mit auffallend wenig Mitochondrien, jedoch relativ zahlreichen freien Ribosomen. Eine mögliche funktionelle Bedeutung dieser beiden morphologisch unterschiedlichen kleinen Lymphocyten wird diskutiert. Danach werden die Zellen der ersten Gruppe als differenzierte Zellformen, die der zweiten jedoch als immunologisch aktivere kleine Lymphocyten angesehen.
    Notes: Summary The ultrastructure of small lymphocytes of human thoracic duct lymph is described and planimetric studies of their size and nucleus-cytoplasm relationship are made. Two morphologically different small lymphocytes could be recognized; cells with a nucleus with little chromatin and a relatively light cytoplasm inclosing many organelles (Golgifield, Centriol, Mitochondria, Monoribosomes), cells with compact chromatin and dense cytoplasm including only a few mitochondria but many monoribosomes. The possible function of these morphological different small lymphocytes was discussed. The first group is a well differentiated cellform, the second one may contain more immonulogical active small lymphocytes.
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    Anatomy and embryology 137 (1972), S. 153-169 
    ISSN: 1432-0568
    Keywords: Embryology ; Epithelial autophagia ; Histocytochemistry ; Human palate ; Macrophages ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An ultrastructural and a histochemical study of the disintegration of the human fetal palatinal junctional epithelium was carried out. Special attention was focused both on the epithelium proper as well as on participation of the surrounding mesenchyma. Epithelial autophagia was noticed in the form of inclusion bodies with cellular remnants as well as general cellular disintegration. The disintegration was correlated to the cellular activity of acid phosphatase and AS-esterase. The differences between human and non-human material were recorded and discussed. In the surrounding mesenchyma, histiocytes (macrophages) were noticed participating in the epithelial disintegration, while ordinary mesenchymal cells seemed without importance. The study of activity of alkaline phosphatase reveals that the rapidly growing ossification center of the vomer was touching the superior aspect of the epithelial junctional seams, where the epithelial disintegration starts. Based upon the findings the following sequential steps of disintegration were discussed: 1) pressure from the outside (the vomer anlage), 2) epithelial autophagia and 3) heterophagia of epithelial remnants (invading histiocytes). The ultrastructure and histochemistry of the so-called epithelial pearls were described. The intercellular substance of the palatinal processes was found to consist of hyaluronic acid and of chondroitin-4- and/or-6-sulfate. The mutual ratio of the glycosaminoglucuronoglycans was discussed.
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    Anatomy and embryology 137 (1972), S. 106-113 
    ISSN: 1432-0568
    Keywords: Anterior pituitary ; Mouse ; Tissue culture ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Suitability of an ordinary incubation system for the culture of anterior pituitary tissues of mice was examined by electron microscopy. It was found that this system has many advantages over Trowell's standard technique for tissue culture and is particularly suitable for the short-term culture. In this system the pituitary tissue cultures were maintained well for at least two days in a chemically defined tissue culture medium (TC 199) without any additives. Addition of 20% calf serum to the medium extended the period to up to five days. Any attempts to prolong it further, however, failed because of a massive necrosis and a great loss of the histological integrity. In the cultured tissues there an enhancement of the LTH cells and a suppression of the other granulated types of cells were observed. The follicular cells were found to hypertrophy and to actively participate in phagocytosis of cell debris.
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  • 45
    ISSN: 1432-0568
    Keywords: Chick embryo ; Granular pneumocytes ; Granular inclusions ; Lamellar inclusions ; Ultrastructure ; Lung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Les inclusions lamellaires caractéristiques des cellules granuleuses de l'épithélium pulmonaire apparaissent chez le Poulet à 16 jours d'incubation. Elles dérivent d'inclusions granulaires que l'on peut déceler dans l'épithélium dès l'apparition de l'ébauche pulmonaire, à 21/2 jours d'incubation. Nous avons étudié l'évolution de ces deux types d'inclusions lorsque les ébauches pulmonaires sont transplantées sur des hôtes d'âge différent. Lorsque une ébauche pulmonaire jeune (21/2 à 3 jours) est greffée sur un hôte plus âgé (6 jours), l'évolution des inclusions granulaires est fortement stimulée et peut conduire à l'apparition d'organites présentant plusieurs des caractères des inclusions lamellaires. Lorsqu'au contraire, une ébauche pulmonaire est transplantée sur un hôte plus jeune (3 jours), deux cas peuvent se présenter: Ou bien l'épithélium ne contient pas encore d'inclusions lamellaires au moment de la transplantation (ébauche de 14 jours par exemple): le moment d'apparition de celles-ci est alors considérablement retardé et leur différenciation ne devient massive que lorsque les inclusions lamellaires apparaissent dans le poumon de l'hôte; Ou bien les inclusions lamellaires sont déjà différenciées (poumon de 18 jours par exemple): dans ce cas, leur différenciation se poursuit pendant toute la durée de la greffe. Lorsqu'une ébauche pulmonaire est transplantée sur un hôte plus âgé ou plus jeune, l'évolution ultrastructurale de l'épithelium est donc modifiée. Selon les cas, elle est stimulée ou, au contraire, freinée. Des facteurs présents dans le milieu intérieur de l'hôte influencent la différenciation des greffons. Ils pourraient également intervenir dans de développement normal des poumons.
    Notes: Summary The lamellar inclusions of the granular pneumocytes first appear in chick pulmonary epithelium at 16 days of incubation. They are derived from granular inclusions which can already be seen in the epithelium at the time when lung buds become distinct (at 21/2 days incubation). We have studied the fate of these two types of organelles after transplantation of embryonic lungs to hosts of a different age. When a young lung bud (21/2 to 3 days) is grafted into an older host (6 days), the development of the granular inclusions is strongly stimulated, and can lead to the appearance of organelles which exhibit several features characteristic of lamellar inclusions. When an embryonic lung is transplanted to a younger host, two situations can occur: Either the epithelium does not yet contain any lamellar inclusions at the time of transplantation (eg lung at 14 days); these appear after a considerable delay, and differentiate in large quantities only at the time of appearance of the inclusions in the host lungs. Or the lamellar inclusions are already differenciated (eg lung at 18 days), in which case, their differentiation continues in the host. Therefore, when a lung bud is transplanted into either a younger or older host, the ultrastructural development is modified. It is either stimulated or inhibited. Some factors, present in the host internal milieu, influence the differentiation of the grafts. These factors could also play a role in the normal development of the lungs.
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  • 46
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    Acta neuropathologica 21 (1972), S. 253-257 
    ISSN: 1432-0533
    Keywords: Haemangiopericytoma, Cerebral-Secondary ; Histology ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A secondary haemangiopericytoma of the cerebral hemisphere in a woman of 23 is described. It is formed of cells arranged in masses around proliferating blood capillaries, and also in rosette patterns. The tumour cells are separated from the capillary endothelial cells by thick collars of basement membrane in abnormal amounts. The histology of the primary tumour of the sacrum, and of the secondary tumours in the lungs and nervous system, are similar. A metastatic haemangiopericytoma of the central nervous system appears not to have been previously reported.
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    Acta neuropathologica 21 (1972), S. 109-116 
    ISSN: 1432-0533
    Keywords: Infantile Neuro-Axonal Dystrophy ; Motor End Plates ; Nerve ; Spheroïds ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The authors report the ultrastructure of neuromuscular biopsies in three cases of infantile neuro-axonal dystrophy. The presence of spheroïds in peripheral and intramuscular nerves, but also in the motor end plates allows the diagnostic of this disease, without doing cerebral biopsy.
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    Acta neuropathologica 21 (1972), S. 68-75 
    ISSN: 1432-0533
    Keywords: Myelinated Nerve ; Venom ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The fine structure of right sciatic nerves of Swiss white mice was studied after being exposed to a venom solution ofAgkistrodon contortrix laticinctus (broad-banded copperhead) and to 0.9% NaCl solutions for periods of 1, 2 or 3 h. There was some “Wallerian-like” degeneration in all groups of nerves in the experiment. Additional neuropathological changes were noted in the nerves exposed to venom solutions. The connective tissue was affected most severely, while the basal lamina was unaffected. Schwann cells were vacuolated, and in the most extreme case, a type of myelin splitting occurred which was considered as a “demyelinative” effect. The results were compared to those of Martin and Rosenberg (1968) [15] on studies of the giant squid axon. References to additional fine structural studies of various other neuropathies were given.
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  • 49
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    Acta neuropathologica 21 (1972), S. 239-252 
    ISSN: 1432-0533
    Keywords: Ultrastructure ; Myotendon ; Zebra-Bodies (ladder-like structure) ; Rods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ultrastructure of the adult and foetal human myotendon is described. At the myotendon the muscle fibre is surrounded by plasma and basement membranes which are never penetrated by the adjacent collagen fibrils of the tendon. Increased thickness and electron density of the plasma membrane and the myofilaments which merge with it occur at the myotendon and this electron dense zone corresponds to the terminal Z-line of the final sarcomere of the myofibril. In the adult the muscle fibre near the myotendon may contain nemaline rods and zebra-bodies. The tendon in the foetus shows much more activity of the fibroblasts than in the normal adult. The collagen fibrils of the early foetus are thinner in diameter than at later stages of development. The union of the tendon with cartilage is illustrated.
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  • 50
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    Calcified tissue international 9 (1972), S. 238-242 
    ISSN: 1432-0827
    Keywords: Dentine ; Ultrastructure ; Tubule ; Tooth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé L'étude ultrastructurale de la dentine humaine périphérique, de couronnes dentaires de sujets âgés de 11 à 75 ans, a montré trois aspects principaux du contenu des canalicules en coupe transversale. Il s'agit de canalicules apparemment vides, de canalicules contenant un matériel organique annulaire et, enfin, de canalicules totalement remplis d'un matériel organique d'aspect granulaire ou hyalin. Aucune terminaison nerveuse n'est visible à ce niveau.
    Abstract: Zusammenfassung Die ultrastrukturelle Untersuchung von peripherem menschlichem Zahnkronendentin bei Patienten im Alter von 11–75 Jahren hat drei Hauptaspekte des Inhaltes der Dentintubuli gezeigt. Sie bestehen bei transversalen Schnitten aus toten Gängen sowie beim Lumen der Tubuli entweder aus ringförmigen oder ganzausfüllenden Ablagerungen. Im äußeren Dentin wurden keine Nervenendigungen beobachtet.
    Notes: Abstract An ultrastructural study of peripheral human coronal dentin in patients aged 11 to 75 years, has shown main aspects of the dentinal tubular content. In transverse sections, they consist of dead tracts and annular or solid content to the tubular lumen. No nerve endings were observed in the outer dentin.
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    Journal of cancer research and clinical oncology 77 (1972), S. 279-291 
    ISSN: 1432-1335
    Keywords: Lung mouse tumors ; Chemical carcinogen ; Ultrastructure ; Pneumocyte II ; Crystalline inclusions ; Interstitial fibrosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary The pulmonary tumours induced in Swiss mice by NMUR seem to be constituted for the most part by cells closely related to the granular pneumocytes (pneumocytes II ou B). Other rarer cells, of epithelial bronchiolar aspect, may take part in the proliferation. The ultrastructural study of tumoral cells suggest that their secretory functions are disturbed. The origin of the crystalline intratumoral structures is discussed, as well as their possible relationship with the production of surfactant. The peritumoral areas are characterized by a dense interstitial flbrosis in which the collagen fibers are associated with an elastoid substance.
    Notes: Resumé Les tumeurs pulmonaires induites chez la souris swiss par le NMUR apparaissent essentiellement constituées de cellules apparentées aux pneumocytes granuleux (pneumocytes II ou B). D'autres cellules plus rares, de morphologie épithéliale bronchiolaire peuvent participer á la prolifération. L'étude ultrastructurale des cellules tumorales suggère que leurs fonctions secrétoires sont perturbées. Le mode de formation des structures cristallins intratumorales est discuté, ainsi que leur rapport éventuel avec la production du surfactant. Les territoires péri-tumoraux sont caractérisés par une fibrose interstitielle dense où les fibres de collagène sont associées à uns substance élastoïde.
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  • 52
    ISSN: 1432-5233
    Keywords: Cyclophosphamide treatment ; Guinea pig ; Experimental diabetes ; Immunodiabetes ; Immunosuppression ; Insulin resistance ; Islets of Langerhans ; Precipitating insulin antibodies ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Hyperglycémie, amélioration de la tolérance à l'insuline et modifications considérables à niveau des cellules B et A des ilots de Langerhans ont fait l'objet d'une observation, après immunisation par insuline et adjuvant, en cobayes produisant des anticorps anti-insuline précipitants. Le traitement par le cyclophosphamide inhibait la production d'anticorps anti-insuline, alors que la glycémie et la tolérance à l'insuline restaient aux mêmes niveaux qu'on pouvait vérifier chez les animaux de contrôle non immunisés. Même les îlots de Langerhans semblaient avoir subi des dommages moins importants par rapport à ceux des animaux qui n'avaient pas été traités par le cyclophosphamide.
    Abstract: Resumen En covayos productores de anticuerpos antinsulina precipitantes, tras inmunización con insulina y adyuvante, se ha podido observar: hiperglicemia, aumento de la tolerancia a la insulina y conspícuas modificaciones a cargo de las células A y B de las islas de Langerhans. El tratamiento con ciclofosfamida inhibía la producción de anticuerpos antinsulina, mientras la glucemia y la tolerancia insulínica permanecían en los mismos niveles que podían observarse en los animales de control no inmunizados. Las islas de Langerhans aparecían menos dañadas respecto a las de los animales no tratados con ciclofosfamida.
    Notes: Riassunto Iperglicemia, aumento della tolleranza all'insulina e cospicue modificazioni a carico delle cellule B ed A delle isole di Langerhans sono stati osservati, dopo immunizzazione con insulina in adiuvante, in cavie produttrici di anticorpi anti-insulina precipitanti. Il trattamento con ciclofosfamide inibiva la produzione di anticorpi anti-insulina, mentre la glicemia e la tolleranza insulinica rimanevano agli stessi livelli riscontrabili negli animali di controllo non immunizzati. Anche le isole di Langerhans apparivano meno danneggiate rispetto a quelle degli animali non trattati con ciclofosfamide.
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    Acta diabetologica 9 (1972), S. 655-687 
    ISSN: 1432-5233
    Keywords: Chinese hamster ; Diabetes ; Glycogen infiltration ; Kidney ; Nuclear glycogenosis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Cette enquête sur l'ultra-structure du rein de hamsters chinois atteints de diabète a permis de relever des lésions glomérulaires légères, consistant en un épaississement non-homogène des membranes basales des vaisseux capillaires, des altérations de cellules de la mésange, une dilatation irrégulière des anses vasculaires. Sur la partie tubulaire, une accumulation de glycogène dans le cytoplasme des cellules de la partie distale et du tube collecteur ainsi que la présence de glycogène dans le noyau des animaux atteints d'un grave diabète et de kétose.
    Abstract: Resumen La presente investigación sobre la ultraestructura del riñón del hamster chino diabético, ha dado la posibilidad de poner en evidencia sutiles lesiones glomerulares, consistentes en el engrosamiento no homogéneo de las membranas basales de los vasos capilares, en alteraciones de las células del mesangio, en la dilatación irregular de las ansas; y, a cargo de la parte tubular, en una acumulación de glicógeno en el citoplasma de las células del tramo distal y del túbulo colector y en la presencia de glicógeno en el núcleo de los animales con diabetes grave y quetosis.
    Notes: Riassunto La presente indagine sulla ultrastruttura del rene di hamsters cinesi diabetici ha fatto rilevare fini lesioni glomerulari, consistenti in ispessimento non omogeneo delle membrane basali dei vasi capillari, alterazioni delle cellule del mesangio, dilatazione irregolare delle anse vascolari. A carico della parte tubulare, accumulo di glicogeno nel citoplasma delle cellule del tratto distale e del tubulo collettore; presenza di glicogeno nel nucleo negli animali con diabete grave e chetosi.
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    Cell & tissue research 126 (1972), S. 193-205 
    ISSN: 1432-0878
    Keywords: Spermatozoon ; Chilopoda ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé Le spermatozoïde de Lithobius forficatus L. a été étudié grâce aux microscopes électroniques, classique et à balayage. Le spermatozoïde a une longueur d'environ 2 mm et comprend deux parties: la tête, avec l'acrosome et le noyau, et la queue, divisée en zone de liaison, pièce intermédiaire et pièce terminale. L'acrosome, entouré par du matériel fibrillaire exogène, a environ 4 μ de long sur 0,2–0,3μ de large. Le noyau spiralé (300 à 400 μ de long) est constitué d'un axe fibrillaire et d'une spire granulaire dans la région postérieure. La zone de liaison est composée de la partie basale différenciée du noyau et des parties antérieures du complexe flagellaire et de la pièce intermédiaire. La pièce intermédiaire, particulièrement longue (1,5 mm environ) est formée par le flagelle entouré de ses gaines et du manchon mitochondrial. La pièce terminale est un court prolongement flagellaire (6 à 7 μ). Les spermatozoïdes matures (prélevés dans les vésicules séminales) ont une structure mitochondriale légèrement différente de celle des spermatozoïdes prélevés dans le testicule.
    Notes: Summary The spermatozoon of Lithobius forficatus was investigated by transmission and scanning electron microscopy. The spermatozoon has a length of about 2 mm long, it is subdivided into a head with acrosome and nucleus, and a tail with a connecting piece, a middle piece and an end piece. The acrosome, surrounded by exogenous fibrillar material is about 4 μ long and 0.2–0.3 μ wide. The spiral nucleus (300–400 μ in length) consists of a fibrillar axis and of a whorl of granular material in the posterior part. The connecting piece is composed of the basal differentiated part of the nucleus and the anterior parts of the flagellar complex and middle piece. The latter is particularly long (about 1.5 mm) and consists of the flagellar complex and the mitochondrial sheath. The flagellar end piece is short (6–7 μ). Mature spermatozoa (seminal vesicles) have a mitochondrial structure slightly different from those within the testis.
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    Cell & tissue research 127 (1972), S. 1-8 
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    Keywords: Parathyroids ; Anurans ; Crystals ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Cytoplasmic and nuclear crystalline inclusions are described in parathyroid secretory cells of adult frogs (Rana temporaria L.) and their possible significance is discussed.
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  • 56
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    Cell & tissue research 127 (1972), S. 34-49 
    ISSN: 1432-0878
    Keywords: Cephalic kidney insects ; Diplura ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé L'ultrastructure du rein labial céphalique deCampodea chardardi Condé a été étudiée. Cette néphridie comprend trois parties: le saccule terminal, le labyrinthe et le canal excréteur. Les cellules du saccule sont des podocytes typiques, contenant de nombreuses vacuoles de pinocytose et des inclusions diverses. La lumière est envahie par des micro-organismes bacilliformes. Le labyrinthe possède des cellules à indentations basales profondes avec de nombreuses mitochondries, et des microvilli distaux. Le canal excréteur débouchant sur la face ventrale du labium est caractérisé par la présence d'une intima cuticulaire. Le rein labial des Diploures a été comparé avec des organes segmentaires néphridiens d'autres Arthropodes, et avec le néphron des Vertébrés.
    Notes: Summary The ultrastructure of the cephalic labial kidney ofCampodea chardardi Condé has been studied. Each nephridium is subdivided into three segments: end-sac, coiled tubule and efferent-duct. The cells of the sacculus are typical podocytes, and contain numerous pinocytotic vesicles and various vacuoles. The lumen contains micro-organisms. The cells of the coiled tubule bear basal infoldings with numerous mitochondria and distal microvilli. The efferent duct terminates close to the ventral face of labium, and possesses characteristic cuticular intima. The labial kidney of Diplura is compared with published data on the nephridial organs of other Arthropods and Vertebrate nephron.
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    Cell & tissue research 127 (1972), S. 175-188 
    ISSN: 1432-0878
    Keywords: Vitelline membrane ; Chorion ; Ephestia ; Follicle cell ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ultrastructural studies on developing egg chambers of the moth, Ephesita kühniella reveal that the precursors of the vitelline membrane are synthesized within follicle cells which are in contact with the oocyte. The vitelline membrane precursors appear to be synthesized by the rough-surfaced endoplasmic reticulum, and this material apparently moves to the Golgi cisternae where the definitive vitelline membrane precursor body is produced. The previtelline bodies are then secreted into the spaces between the oocyte and follicle cells, where they fuse to form a continuous membrane. Chorion formation begins with the deposition of a layer of tubules at the outer edge of the vitelline membrane which coalesce to form the inner edge of a thin, striated layer. In subsequent stages, several compartmented layers are rapidly secreted external to the striated layer, giving rise to the mature chorion.
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  • 58
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    Cell & tissue research 127 (1972), S. 356-373 
    ISSN: 1432-0878
    Keywords: Complex eye ; Formica polyctena ; Receptors ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die Analyse der Feinstruktur des Komplexauges der Ameise Formica polyctena ergab, daß der dioptrische Apparat der insgesamt 750 Ommatidien aus einer lamellierten Cornealinse und einem euconen Kristallkegel besteht. Zwei Hauptpigmentzellen umgeben schalenförmig den Kristallkegel, 8 Nebenpigmentzellen schirmen das Ommatidium in seiner ganzen Länge von der Cornea bis zur Basalmembran ab. Jedes Ommatidium besteht in seinem distalen Teil aus 8 Retinulazellen, 2 gegenüberliegenden schmalen und je 3 gegenüberliegenden großen Sehzellen. Weiter proximal tritt eine 9. Retinulazelle hinzu. Die Mikrovillisäume der Sehzellen verschmelzen zu einem zentralen Rhabdom. Im distalen Teil sind die Mikrovilli in 3 Richtungen angeordnet. Es wird im besonderen die Orientierung der Mikrovilli zur Augenlängsachse und zur Ommatidien-Symmetrieachse untersucht. Auch die 9. Sehzelle bildet Mikrovilli. Das Rhabdom endet an 4 basalen Pigmentzellen. Auf den Mikrovillisaum folgt im Querschnitt des dunkel adaptierten Ommatidiums ein Kranz von großen intrazellulären Vakuolen. Die anschließende cytoplasmatische Zone der Retinulazellen enthält viele Pigmentgranula und Mitochondrien; multivesikuläre und multilamelläre Körper sowie Golgiapparate treten nur selten auf. Die funktionelle Bedeutung des Ommatidienaufbaues und die Verteilung der Organellen bei Dunkeladaptation werden diskutiert.
    Notes: Summary The fine structure of the compound eye of the ant Formica polyctena was investigated. The eye consists of a total of 750 ommatidia, each containing a dioptric apparatus of a lamellated cornea lens, a eucone-type crystalline cone, and 8 long pigment cells which surround the ommatidium for its total length, i.e. from the cornea to the basal membrane. Each ommatidium has in its distal portion 8 retinula cells—6 large plus 2 small ones. The retinula cells are arranged in such a way that 3 pairs of large cells, and the one pair of the small cells lie opposite each other. Further proximally, a 9th retinula cell is encountered. The fused, centrally located rhabdom is built up by the microvilli of all nine retinula cells. The rhabdom ends at 4 basal pigment cells. In dark adapted ommatidia, a ring of large intracellular vacuoles is to be seen immediately peripherally to the rhabdom. The outer, cytoplasmic zone of the retinula cells contains many pigment granules and mitochondria; multivesicular bodies, onion bodies and Golgi apparatus are of relatively rare occurrence. The functional significance of the ommatidial structure and the arrangement of the cell organelles in the dark adapted condition are discussed.
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  • 59
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    Cell & tissue research 124 (1972), S. 465-478 
    ISSN: 1432-0878
    Keywords: Anterior pituitary ; Mouse ; in vitro ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Anterior pituitaries of mice were incubated for periods up to four hours in Krebs-Ringer bicarbonate glucose gassed with 95% O2∶5% CO2. The incubated explants survived and retained a fine structure that approximated the condition in situ. The few necrotic cells were sharply localized, and were found to be due to initial mechanical damage to the tissue. Some cells of the six granulated types exhibited slight but significant changes attributable to the liberation from the hypothalamic control: in LTH cells there was a release of preexisting granules and a development of cell organelles, whereas in other cell types there was an inhibition of release of granules and an enhanced digestion of the accumulated granules by the lysosomal system. Follicular cells responded uniquely to the changed environment by hypertrophy of the cytoplasm and were found to phagocytize cell debris. A part of non-epithelial elements of the gland showed a tendency to modulate cytologically.
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    Cell & tissue research 124 (1972), S. 454-464 
    ISSN: 1432-0878
    Keywords: Lateral-line organ ; Eel (Anguilla japonica) ; Mechanoreceptor ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The sensory epithelium of the lateral line organ of the common eel consists of two types of cells, (sensory and supporting). The sensory cell bears a kinocilium together with about 40 to 60 stereocilia on its surface. The kinocilium is situated either at rostral or at caudal margin of this cilial group. Such polarity of the cilial group of one cell is inverse to that of an adjacent cell. Two types of crystal-like inclusions exist in the sensory cells, consisting of granules 100 Å in diameter. Granules in one type are arranged regularly whereas those in the other rather irregularly. Two types of nerve endings exist at the base of sensory cells: one is predominant in number and contains few vesicles, accompanied by a dense spherical body surrounded by small vesicles in the sensory cell and the other is rare in number and contains many vesicles, accompanied by a small flat sac just beneath the plasma membrane of the sensory cell. The supporting cells contain numerous mitochondria, a well developed Golgi apparatus and rough-surfaced endoplasmic reticulum, and surround a sensory cell completely. Physiologic significance of some of these components is discussed.
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    Cell & tissue research 126 (1972), S. 335-347 
    ISSN: 1432-0878
    Keywords: Glandulae submaxillares ; Mammals ; Duct cell granules ; Ultrastructure ; Histochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Discrete, PAS-positive granules of relatively uniform electron-density and size characterise the intercalated duct cells of mammalian submaxillary glands. Smaller, electron-dense organelles are seen in the cells at the junction of the intercalary-striated duct region in the guinea-pig. The large granules of variable electron-density which are observed in the proximal, modified intercalary cells in the rabbit closely resemble the granules in the acinar cells of the guinea-pig. Several populations of granules differing in size are found in the striated granular tubules of the rat and hamster; the organelles in the rat show two grades of electron-density whereas those in the hamster are uniformly dense. Numerous small granules with compactly arranged intragranular material occupy the apical part of the striated ducts of the cat, dog and rabbit. The chemical composition of each population of duct cell granules is unknown. The question whether granules containing kallikrein, trypsin-like enzymes and amylase are stored in the duct cells is discussed.
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    Cell & tissue research 126 (1972), S. 437-445 
    ISSN: 1432-0878
    Keywords: Eye ; Sarcophaga bullata ; Ommatidia ; Lamina ganglionaris ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary External and internal surfaces of the compound eye of the flesh fly, Sarcophaga bullata, were examined with a scanning electron microscope. A low patterned corneal nippleridge array and sparse setiform interfacetal hairs were observed on the corneal lens surface. Particular cleavage planes revealed outlines of the Semper Cells, their nuclei and distal terminations of photoreceptor cells. The latter, with their axonal processes, were visualized and described. These axons were noted traversing the external chiasma and entering the lamina ganglionaris where suggestions of synaptic contact were pointed out. The present descriptions were correlated with those taken from literature of the transmission electron microscope.
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    Cell & tissue research 127 (1972), S. 201-208 
    ISSN: 1432-0878
    Keywords: Spermatogenesis ; Rat ; Mitosis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The pattern of intercellular cytoplasmic bridges between rat spermatogonia and between spermatocytes is illustrated from electron microscopy of serial sections. Clones, or syncytia, containing as many as 22 connected spermatogonia and as many as 74 connected spermatocytes were observed. The absence of closed rings of cells agrees with the observation that intercellular bridges are the result of incomplete cell division, rather than cell fusion. The bridges thus are a record of spermatogonial divisions within a clone. In early spermatogonial generations there is a predominantly linear arrangement. The groups of spermatocytes have more side branches. From the presence of synaptonemal complexes it is concluded that the connected spermatocytes of a given clone are in about the same developmental stage. The pattern of intercellular bridges indicates, however, that not all nuclei in a clone undergo mitosis in the same cycle. The connected cells of a clone are therefore not all of the same generation. From unconnected bridges it is assumed that new clones originate from single cells or groups of spermatogonia which separate from an existing clone.
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    Cell & tissue research 130 (1972), S. 302-311 
    ISSN: 1432-0878
    Keywords: Gonadal development ; Sex determination ; Germ cells ; Mollusca ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The development of the gonad, from hatching through sexual maturity and oviposition, has been studied in Arion ater rufus and Deroceras reticulatum. At hatching, the gonad is comprised of several acini. These acini are hollow structures, the walls of which are generally one or two cell layers thick. This cell layer consists of intermingled germinal and non-germinal cells. Eventually, each acinus is divided into two compartments (cortical and medullar) by a layer of auxiliary cells. The auxiliary cells appear to differentiate into Sertoli and follicle cells. These three non-germinal cell types appear to form an uninterrupted cell barrier that isolates the female germ cells in the cortex from the male germ cells in the medulla. Thus, although these animals are hermaphroditic, the male and female germinal lines differentiate in physiologically isolated compartments.
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    Cell & tissue research 130 (1972), S. 279-301 
    ISSN: 1432-0878
    Keywords: Gonadal development ; Sex determination ; Germ cells ; Mollusca ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A cytological study has been made, at the light- and electron-microscope levels, of gonadal development in Arion circumscriptus. The gonad appears to be ectodermal in origin and is composed of two cell lines—germinal and non-germinal. These two lineages are established in the embryo. The germinal line is first represented by primordial germ cells while the non-germinal line is first represented by auxiliary cells. The primordial germ cells differentiate into spermatogonia and oogonia, the auxiliary cells into Sertoli cells and follicular cells. Spermatogonia and oogonia differentiate about the time of hatching. All subsequent germ cells appear to differentiate from these initial populations of spermatogonia and oogonia. The concept of a germinal epithelium, as a cell layer in which germ cells differentiate from indeterminate germ cells throughout the life cycle, is not supported by this study. A model for sex determination of the germ cells is proposed based on the hypothesis that sexually non-determined primordial germ cells are distributed into two physiologically isolated compartments (a male medullar compartment and a female cortical compartment). The spermatogonia and oogonia then differentiate in two different microenvironments.
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  • 66
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    Cell & tissue research 131 (1972), S. 31-45 
    ISSN: 1432-0878
    Keywords: Synapse ; Ultrastructure ; Giant fibre ; Crayfish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of synapses between the cord giant fibres (lateral and medial) and the motor giant fibres in crayfish, Astacus pallipes, third abdominal ganglia have been examined. These electrotonic synapses are asymmetrical, they have synaptic vesicles only in the presynaptic fibre, and they have synaptic cleft widths normally of about 100 Å but narrowed to about 50 Å in restricted areas. Localized increases in density of the synaptic cleft and adjacent membranes also occur within a synapse, and synaptic vesicles are most tightly grouped at the membrane in such areas. Tight or gap junctions with 30 Å or narrower widths have not been found, but the junctions probably function in a similar way to gap junctions. Three small nerves are closely associated with the synapses between the giant fibres. One of these small nerves has round synaptic vesicles and is thought to be excitatory on morphological grounds; one has flattened vesicles and is thought to be inhibitory; and one is postsynaptic to the lateral giant and the two small presynaptic nerves. It is proposed that these small nerves modulate activity in the much larger giant fibre synapse.
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    Cell & tissue research 131 (1972), S. 47-62 
    ISSN: 1432-0878
    Keywords: Neurohypophysis ; Lungfish ; Ultrastructure ; Histochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The neurohypophysis of the South American lungfish Lepidosiren paradoxa has been studied with light and electron microscopy, including the Falck-Hillarp technique for catecholamines. The pars nervosa hypophyseos is a well-marked, dorsally located subdivision of the pituitary gland composed of lobes or follicles, each one constituted of a central core of ependymal cells, a subependymal hilar region made up of nerve fibers and a peripheric palisade zone of nerve endings which contact capillary vessels. Four types of neurosecretory axons can be distinguished under the electron microscope. Type I, the most common, contains spherical elementary granules of high electron density, 1500–1800 Å in diameter. The scarce type II axons contain irregularly-shaped elementary granules. Type III contains only small clear vesicles, 400–600 Å in diameter. Type IV, mostly present in regions of the gland contacting the pars intermedia, contain large granulated vesicles, 900–1000 Å in diameter. The Falck-Hillarp technique revealed axons with a positive reaction for catecholamines at sites corresponding approximately to the location of type IV of the electron microscope. Ependymal cells are of large size, linking the cerebrospinal fluid, the nerve endings and the blood vessels. A conspicuous membrane-bound, spherical dense material, 1400–2000 Å in diameter, is observed in both the apical and vascular processes of these cells. The ependymal processes which traverse the hilar and palisade regions contain structures resembling degenerated neurosecretory axons. These results are discussed in relation with the currently available information on the comparative anatomy of the pars nervosa. The possible functional significance of ependymal cells and of each type of axon are also discussed. This study was aided by the following grants: NIH NS 06953 to Prof. De Robertis, Consejo Nacional de Investigaciones Científicas y Técnicas to Prof. Zambrano, Comisión de Investigaciones Científicas de la Provincia de Buenos Aires and Comisión de Investigaciones Cientificas de la Universidad Nacional de la Plata: to Prof. Iturriza. The authors are indebted to Prof. De Robertis for his generosity in granting us his laboratory facilities, and to Dr. F. J. J. Risso and Mr. A. Fernández (Resistencia, Chaco) who provided the specimens used in this study. The able microtechnical assistance of Miss L. Riboldazzi and Mrs. R. Raña and the photographic work of Mr. A. Saenz are much appreciated.
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    Cell & tissue research 132 (1972), S. 193-201 
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    Keywords: Branchial glands ; Cephalopods ; Haemocyanin synthesis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The paired branchial glands in cephalopods are essential for life. The electron microscope reveals them to consist of cells containing masses of endoplasmic reticulum organised in parallel arrays together with pale areas between the reticulum that contain vacuoles. All three regions of the cells contain masses of haemocyanin particles and it is suggested that the gland is the site of haemocyanin synthesis, the particles being made amongst the endoplasmic reticulum at discharged into the pale areas and vacuoles before being released into the general circulation.
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  • 69
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    Keywords: Islets of Langerhans ; Grass-snake ; Crystalline B-granules ; Ultrastructure ; Crystallography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Kristalline B-Granula im Pankreas der Ringelnatter besitzen die Form von Rhombendodekaedern (a ≈ 11 nm, kubisch-raumzentriertes Gitter). Diese Diagnose wird abgeleitet von den Ergebnissen der dreidimensionalen Rekonstruktion von Serienschnitten, der optischen Diffraktometrie und aus dem Vergleich mit Kristallmodellen. Die Bedeutung kristalliner B-Granula wird erörtert.
    Notes: Summary Crystalline B-granules of grass-snake islets of Langerhans have been shown to possess the shape of rhombic dodecahedra (a ≈ 11 nm, cubic body-centered lattice). Three-dimensional reconstructions from serial sections, optical diffractometry and comparison with crystal models were the techniques utilized. The significance of crystalline B-granules is discussed.
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    Cell & tissue research 132 (1972), S. 15-24 
    ISSN: 1432-0878
    Keywords: Digestive diverticula ; Bivalves ; Peroxisomes ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron microscopy of the digestive diverticula of the protobranch bivalve, Nucula sulcata, revealed the presence of peroxisomes in the basal regions of the epithelial cells lining the main and secondary ducts, and in the digestive and secretory (basophil) cells of the tubules. Those in the secretory cells are elongate and somewhat flattened, while those of the other cell types have a spherical form. Two distinct types of nucleoid are normally present within the secretory cell peroxisomes, one compact, crystalline, and finely polytubular, the other comprising isolated secondary tubules arranged in a linear series across the width of the organelle. The peroxisomes of the digestive and duct cells contain coarsely polytubular cores arranged in two clusters orientated more or less at right angles; the duct cell peroxisomes may also contain a second nucleoid in the form of a compact finely polytubular core. Sections incubated in a medium containing 3,3'-diaminobenzidine (DAB) and hydrogen peroxide reveal an electron dense reaction product within the peroxisomes of all the cell types. Catalase is considered to be responsible for the reaction.
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    Cell & tissue research 132 (1972), S. 67-78 
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    Keywords: Salivary glands ; Octopus ; Secretory fibers ; Synapse ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé Les nerfs sécréteurs pénètrent dans l'épithélium des tubules au niveau du hile de la glande. Leurs subdivisions se disposent entre les cellules épithéliales ou leurs replis, et gardent toujours une situation extracellulaire. Les plus gros faisceaux d'axones sont encore entourés par des cellules satellites qu'on n'arrive plus à discerner autour des faisceaux moins importants ou autour des fibres isolées. Les axones sont alors directement au contact des cellules glandulaires. On a pu trouver des synapses neuro-glandulaires avec des spécialisations membranaires asymétriques comparables à celles décrites dans le système nerveux central des Vertébrés. Les fibres sécrétrices variqueuses contiennent d'autre part des vésicules de types variés, semblables à celles des troncs sécréteurs et moteurs du canal, et à celles des fibres motrices de la glande. La signification de ces vésicules a été discutée en relation avec l'existence possible d'amines biogènes diverses dans les fibres nerveuses.
    Notes: Summary The secretory nerves enter the tubule epithelium at the level of the gland hilus. Their subdivisions being located between the epithelial cells or their infoldings, have always extracellular position. Satellite cells still surround the largest axon bundles, but are no longer discernable round the smaller bundles or isolated axons which are thus in direct apposition with glandular cells. Neuro-glandular synapses, with asymetric membrane specialisations similar to those found in the central nervous system of vertebrates, have been found. The varicose secretory fibers contain various types of vesicles, similar to those found in the secretory or the motor trunks at the duct level, or in the gland motor fibers. The significance of these vesicles is discussed, in reference to the possible existence of various biogenic amines in the nerve fibers.
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    Cell & tissue research 132 (1972), S. 131-146 
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    Keywords: Nervous tissue ; Tardigrada ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Das Nervengewebe von Macrobiotus hufelandi zeichnet sich durch stark verzweigte pseudunipolare Nervenzellen und relativ wenige Gliazellen aus. Die Neurone besitzen rauhes ER, freie Ribosomen, zahlreiche Mitochondrien, einen wenig ausgeprägten Golgi-Apparat und einen elektronenlichten Kern. In ihren Axonen finden sich Vesikel und Einschlüsse unterschiedlicher Größe und Zusammensetzung. Die Gliazellen verzweigen sich stark und besitzen glattes ER, viele freie Ribosomen und einen elektronendichten Kern. Ganglien und Nerven werden nur durch eine dünne Neurallamelle vom extraganglionären Raum getrennt. Die morphologische Ausbildung des Nervengewebes wird im Hinblick auf die extreme Lebensweise der Tardigraden diskutiert.
    Notes: Summary The typical elements of the nervous tissue of Macrobiotus hufelandi are strongly ramified pseudunipolar neurons and a small amount of glial cells. In the perikarya of neurons there are rough ER, free ribosomes, many mitochondria, a poor Golgi-apparatus, and an electron-light nucleus. Nerve fibers contain masses of vesicles and inclusions of different size and composition. The ramifying glial cells have smooth ER, many free ribosomes, and an electron-dense nucleus. Ganglia and nerves are separated from the extraganglionic cavity by a thin acellular sheath (neural lamella). The organization of the nervous tissue is discussed with regard to the extreme conditions of environment of the tardigrades.
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    Cell & tissue research 132 (1972), S. 451-472 
    ISSN: 1432-0878
    Keywords: Adenohypophysis ; Myxine glutinosa ; Cell types ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of adenohypophysial cells in the Atlantic hagfish (Myxine glutinosa) is described and the morphological evidence for secretory activity is discussed. A scarcity of secretory granules is characteristic of the adenohypophysis of Myxine. Two cell types having the appearance of protein hormone producing cells can be identified. Type 1 has dense membrane-bound granules with a calculated mean diameter of 88 nm while type 2 has larger granules with a mean diameter of 176 nm. The release of secretory granular material follows mainly the “membrane-release” pattern. It is suggested that cell type 1 may produce a hormone which is similar to ACTH/MSH and type 2 another hormone similar to STH/LTH. The basophilic cells contain a secretory material which is similar to the mucus produced in the epithelial mucus cells. Several structural modifications are considered to represent functional compensations for the absence of vascular elements in the gland. Among these are a cytoplasmic tubular system, certain long agranular cells together with long granule-containing projections from cell types 1 and 2, and foliate or finger-like invaginations of the basal lamina.
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  • 74
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    Cell & tissue research 133 (1972), S. 35-46 
    ISSN: 1432-0878
    Keywords: Ultrastructure ; Fowl ; Liver
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the liver parenchymal cell from immature pullets and from immature and young mature cockerels has been studied. The results demonstrated that the fowl's hepatocyte is structurally very similar to that of other birds and, in spite of certain morphological differences between the livers of birds and mammals, is also very similar in structure to the liver cell of mammals.
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  • 75
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    Cell & tissue research 130 (1972), S. 312-317 
    ISSN: 1432-0878
    Keywords: Aphid cornicle ; Basal lamina ; Oenocyte ; Holocrine secretion ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Light- and electron-microscopic observations on the cornicles of the rose aphid Macrosiphum rosae are presented, and discussed in relation to conflicting interpretations of cornicle structure and function. Lipid filled cornicle secretory cells occupy the lumen of the cornicle and extend into the abdominal cavity. The aphid is readily induced by mechanical stimuli to release cornicle secretory cells from a pore at the tip of the cornicle. The holocrine secretory cells are disrupted and release their lipid contents on leaving the body. They are enclosed within an acellular membranous sac that is apparently identical in structure with the basal lamina of the epidermis. The ultrastructure and anatomical relationships of the cornicle secretory cells suggest that they are oenocytes invaginated with the epidermal basal lamina, and are not anatomically or embryologically related to fat body.
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  • 76
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    Keywords: Ultimobranchial glands ; Urodeles ; Cell types ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the ultimobranchial (UB) glands of two common laboratory urodeles, viz., larval axolotls, Ambystoma mexicanum Shaw and adult Pleurodeles waltlii Micahelles, is described and compared in what is believed to be the first ultrastructural report on urodele UB glands. The axolotl UB gland shows a wide variety of form, being represented by an elongated diffuse series of follicles and sometimes by one or two large discrete terminal follicular bodies. In these axolotl UB glands up to four cell categories are distinguishable including a tonofilamentous cell and a secretory cell that is possibly homologous with calcitonin-producing C cells of anurans or other vertebrates. These two cell categories are also found in the Pleurodeles gland. The possible significance of the various cells is considered.
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  • 77
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    Cell & tissue research 134 (1972), S. 255-271 
    ISSN: 1432-0878
    Keywords: Hepatopancreas ; Limulus ; Gap junctions ; Calcium spherules ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the hepatopancreas and associated tissues of Limulus is described. All hepatopancreatic tubules contain L- and D-cells. L-cells exhibit apical pinocytosis and contain many different types of inclusions, including lipid containing calcium spherules of unique structure. They also produce a complex secretory product released by apocrine secretion. D-cells contain much rough endoplasmic reticulum, and show other evidence of active protein synthesis. They produce a single type of secretory granule released by merocrine activity. The appearance of L- and D-cells in tubules of various sizes and in fed and starved animals is described. Both cell types may produce digestive enzymes and absorb and transport nutrients to the hemolymph, but neither serves as a major storage site. Storage is an important function of the intertubular R-cells. The appearance of R-cells in fed and starved animals is described. A previously undescribed hemocyte is reported, as are apparent gap junctions between L- and R-cells. A structural and functional comparison of these glands with those of other arthropods is presented.
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  • 78
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    Cell & tissue research 134 (1972), S. 273-282 
    ISSN: 1432-0878
    Keywords: Swim Bladder ; Gas gland cells ; Misgurnus fossilis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the wall of the rudimentary rear chamber in the swimbladder of the pond-loach was studied. The morphological features of a majority of the cells, as well as the presence of micro-rete mirabile, suggest that epithelial components in the wall of this organ represent a structural and functional equivalent of the gas gland.
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  • 79
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    Cell & tissue research 131 (1972), S. 429-436 
    ISSN: 1432-0878
    Keywords: Hormone granules ; Thyroid (C-cells) ; Anterior Pituitary ; Ultrastructure ; Freeze-etching method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Gefriergebrochene Präparate (mit und ohne Ätzung) der Adenohypophyse und der C-Zellen der Schilddrüse von Ratte und Meerschweinchen wurden elektronenmikroskopisch untersucht. Bei den Hormongranula dieser Zellen verlaufen die Bruchflächen im allgemeinen zwischen den beiden Membranflächen oder zwischen Granulum-Inhalt und Membran. Nur relativ selten werden Granula quergebrochen. Auf beiden Hälften der gespaltenen Membranen der C-Zellgranula werden etwa mit gleicher Häufigkeit Proteinpartikel (100–200 Å) gefunden. Bei den Granula der somatotropen Zellen treten auf der dem Plasma anliegenden Membranhälfte deutlich mehr Proteinpartikel auf als auf der dem Granuluminhalt anliegenden Hälfte. Der Inhalt der somatotropen und C-Zellgranula erscheint bei dieser Präparationsmethode aus einer dichten Packung von 80–100 Å großen Partikeln zu bestehen. Eine besonders strukturierte Zone zwischen Membran und Granuluminhalt konnte bei den bisherigen Untersuchungen nicht festgestellt werden. Durch Ätzung der Gefrierbrüche ließen sich keine zusätzlichen strukturellen Details der Granula darstellen. Eine durch Auswertung von stereoskopischen Aufnahmen gewonnene Größenverteilungskurve für die C-Zellgranula wird vorgelegt.
    Notes: Summary Freeze-fractured preparations (with and without etching procedures) of guineapig and rat thyroid (C-) cells and anterior pituitary (somatotropic-) cells have been investigated with the electron microscope. The hormone granules of these cells in general split either between the two lamellae of their unit membrane or between the granule contents and the unit membrane. Only rarely cross-broken granules have been observed. Inner and outer lamella of the unit membrane of the C-cell granules contain in more or less similar frequency moderate amounts of protein particles of 100–200 Å diameter. In case of the somatotrophs the outer lamella contains higher numbers of these particles than the inner one. The contents of the C-cell and somatotroph granules seems to consist of densely packed 80–100 Å particles. A particular zone between contents and membrane (as observed on micrographs with conventional electron microscopy) could not be detected on freeze-fractured preparations. The etching procedure does not reveal additional details of the granule structure. A size distribution curve of the C-cell granules as determined from stereo-pairs, is given.
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    Cell & tissue research 131 (1972), S. 497-517 
    ISSN: 1432-0878
    Keywords: Granulosa cells ; Oocyte ; Pig ; Mitochondria ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Pig oocytes and their surrounding granulosa cells obtained from mature Graafian follicles at a stipulated time near to ovulation were studied in some details electronmicroscopically. Particular emphasis is given to the corona radiata cell processes and to the heterogeneous population of mitochondria in the oocyte. The corona radiata cell processes contain various components such as filaments, mitochondria, multivesicular bodies and lipid droplets in their matrix. The contact relationship of the corona radiata cell processes to the oocytes is maintained by desmosomes. Usually, the two parallel surface membranes forming the desmosome are separated by a space of about 200 Å. Occasionally, the two membranes approximate each other to form a junction having a “gap” of about 70 Å. Apparently the membranes become fused in some regions. Of particular interest is the distribution and structural characteristics of the single-membrane-bounded structures, and their relationship to the cytomembranes and the mitochondria. On the basis of the present and earlier (Norberg, 1972) observations, the question arises whether the formation and development of mitochondria of pig oocytes depend, at least partly, on a metamorphosis of single-membrane-bounded structures derived from less complex membraneous elements. Final conclusions concerning this problem demand integrated morphological and biochemical investigation regarding the biosynthesis of mitochondria.
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  • 81
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    Cell & tissue research 132 (1972), S. 25-34 
    ISSN: 1432-0878
    Keywords: Neurohypophysis ; Rat ; Perivascular cells ; Neurosecretion ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The purpose of this study is to investigate the ultrastructural features of perivascular cells as found in the neural lobe of the hypophysis. In particular, an inquiry was made into the nature of the relationship of such cells to neurosecretory fibers and endings. The latter, in fact, are often invaginated within the perivascular cells and enveloped by their processes; furthermore, they often reveal a certain number of empty granules as well as characteristics of degenerative nature. In the course of this study the localization of the perivascular cells has been investigated as well as that of their processes within the extensive interlobular network typical of the hypophysial neural lobe of rodents. Based on the data gathered, the hypothesis is put forward that the perivascular cells play an important role in the turnover of neurosecretory endings, both under physiological and experimental conditions, contributing thereby to the release of post-hypophysial hormones.
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  • 82
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    Cell & tissue research 132 (1972), S. 51-65 
    ISSN: 1432-0878
    Keywords: Salivary glands ; Octopus ; Innervation of musculature ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé Les fibres nerveuses, souvent composées, qu'on peut trouver dans le tissu conjonctif séparant les fibres musculaires du canal, ou les tubules de la glande, sont très comparables morphologiquement aux fibres des troncs moteurs. Leurs cellules satellites, qui contiennent de grosses inclusions, nombreuses et très denses aux électrons, engainent les axones pratiquement jusqu'au niveau des terminaisons. Les jonctions neuromusculaires sont caractérisées par l'accumulation de petites vésicules claires, accompagnées de quelques vésicules plus grandes et à »coeur« dense. Les axones présentent aussi le long de leur trajet des segments plus ou moins dilatés où existent des vésicules de types très variés, et dont la signification est discutée.
    Notes: Summary Nervous fibers, often composite, can be found in the connective tissue between the duct muscular fibers, or the gland tubules. They are morphologically similar to the motor trunks fibers. Their satellite cells, containing numerous electron-opaque large inclusions, can be seen round the axons nearly to the nerve endings. Neuromuscular junctions are characterized by the accumulation of small clear vesicles, intermingled with some larger dense-cored vesicles. Axonal swellings, with numerous vesicles of various types, can also be seen along the course of the nerve fibers; their significance is discussed.
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    Cell & tissue research 132 (1972), S. 95-106 
    ISSN: 1432-0878
    Keywords: Olfactory sensilla ; Insects ; Necrophorus ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung 1. Auf dem Endglied der Antenne von Necrophorus wird eine neue Sensillenform als Sensillum coelosphaericum beschrieben. Anhand von Merkmalen des cuticulären Apparates werden 2 Typen dieses Sensillums unterschieden. 2. Die Wand des cuticulären Apparates ist von einem Porensystem durchbrochen, das als reizleitende Struktur angesehen werden kann. Abweichend vom Porensystem basiconischer Sensillen finden sich bei den Sensilla coelosphaerica statt der Porentubuli sackförmige Bildungen, die aus einem dreidimensionalen Gitterwerk von miteinander vernetzten Filamenten bestehen. Diese Filamentsäcke enden bei Sensillum coelosphaericum Typ I in Einbuchtungen der 3. Hüllzelle, die hier den cuticulären Apparat auskleidet; bei Typ II grenzen sie an den äußeren Liquorraum. 3. Bei beiden Typen der Sensilla coelosphaerica werden die Dendriten auch innerhalb des cuticulären Apparates von einer Scheide umgeben. Das reizleitende System reicht nicht bis in unmittelbare Nähe der Dendriten. Die räumliche Anordnung der Strukturen führt zu der Auffassung, daß Duftmoleküle die Dendritenmembran nicht allein durch Grenzflächen-Diffusion erreichen Können.
    Notes: Summary 1. A new type of olfactory sensilla, named Sensillum coelosphaericum, was found on the distal segment of the antenna of the Carrion beetle Necrophorus. Two types of sensilla are differentiated by characteristics of their cuticular apparatus. 2. The wall of the cuticular apparatus is penetrated by pores which may function in the conduction of stimuli. The sensilla coelosphaerica differ from the basiconic sensilla in that they do not have pore tubules but have sac-like structures consisting of a three-dimensional network of filaments. In sensillum coelosphaericum type I, these sacs end in infoldings of a third enveloping cell which in this type coats the inside of the cuticular apparatus; in type II, on the other hand, the sacs of filaments border the outer liquor space. 3. Within the cuticular apparatus in both types of sensilla coelosphaerica, the dendrites are surrounded by a dendritic sheath. The stimulus-conducting system does not contact the dendrites. The arrangement of these structures implies that odour molecules can also reach the dendrite membrane by other means than surface diffusion.
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    Cell & tissue research 135 (1972), S. 275-286 
    ISSN: 1432-0878
    Keywords: Oöcyte ; Resorption ; Locust ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The changes in the ultrastructure of the oöcyte and associated follicle cells during oösorption in Locusta migratoria migratoroides are described. Throughout the process the follicle cells act in a phagocytic manner and invade the oöplasm. Localizatio of acid phosphatase activity indicates that at the start of resorption the Golgi complexes of the follicle cells begin to produce lysosomes on a large scale, and that these are utilised in the breakdown of yolk spheres which have been taken up from the oöcyte. Partly degraded yolk spheres are collected together along with other cell organelles into cytolysomes. The significance of large numbers of microtubules within the follicle cells and of microvillar borders between the cells in late stage resorbing bodies is discussed.
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    Cell & tissue research 133 (1972), S. 163-179 
    ISSN: 1432-0878
    Keywords: Excretory organ ; Ileum ; Blatella germanica ; Ultrastructure ; Microprobe analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé L'iléon de Blatella germanica est un important segment d'accumulation minérale. Les nombreuses concrétions d'origine ergastoplasmique, contiennent du phosphore, du chlore, du calcium, du magnesium, du potassium et du fer dans un stroma glycoprotéique. La paroi de ce segment protodéal est constituée d'un type cellulaire unique caractérisé par la présence de feuillets apicaux et d'invaginations basales, différenciations membranaires décrites dans d'autres organes de transit, mais dont la coexistence constitue l'originalité de l'iléon. La signification physiologique de ce segment digestif est discutée.
    Notes: Summary The ileum of Blatella germanica is an important proctodeal segment of mineral accumulation. The numerous concretions, elaborated by the ergastoplasm, contain P, Cl, Ca, Mg, K and Fe in a glycoproteic matrix. The epithelium of this segment is composed by only one type of cells which are characterized by apical leaflets and basal infoldings. These membraneous differenciations have been already described in other transit organs, but their coexistence is typical of the ileum. The physiological significance of this digestive segment is discussed.
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    Cell & tissue research 133 (1972), S. 289-325 
    ISSN: 1432-0878
    Keywords: Nematosomes ; Neurons ; Substantia nigra ; Rat and Cat ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Distinctive cytoplasmic inclusions, termed nematosomes, have been identified in the neurons, but not in the glial cells of the substantia nigra in the rat and the cat. These organelles which lack a limiting membrane consist of an entanglement of more or less tightly packed microfilaments or filamentous strands. According to the tridimensional arrangement of their filamentous components, as well as to their size and boundary, the nematosomes usually display several structural types: (a) round or oval, dense, filamentous bodies; (b) reticular inclusions with or without excavated centers; (c) ill-defined small aggregates of fine filaments. At higher magnification, each microfilament or filamentous strand, whatever the type of nematosome, is itself composed of similar subunits, about 20 Å in diameter. It should be pointed out that the latter subunits may be fine deposits of heavy metal on structural components of nematosomes, which appear to be similar in every structure. The ultrastructural organization of a given nematosome may vary from one portion to another. The functional significance of such structural variations from one nematosome to another, and even within a given nematosome, could not be elucidated by means of our ultrastructural study, although additional cytochemical and radioautographic work may throw light on this problem. These cytoplasmic bodies are present in the perikaryon of most neurons and one or more inclusions are usually observed in the same nerve cell. They are infrequently seen in the dendritic or axonal processes. The nematosomes are closely associated with the other cytoplasmic organelles filling the ground substance of neurons by means of microfilaments projecting from their surface. These cytoplasmic inclusions are, however, most frequently linked to surrounding free ribosomes and rough ER profiles. The association of free ribosomes with excavated nematosomes, which in turn contain neurofilaments in their core, suggests that these structures consist, partly at least, of precursor material which is assembled into the structural proteins of the neurofilaments after being synthesized by the neighbouring ribosomes. No special relationship with the neurotubules has been noticed. Nematosomes have also been found in structural relationship with other organelles, i.e. the smooth tubules and vesicles, the Golgi apparatus, the coated vesicles, the lysosomes and the mitochondria. The nematosome may be also closely associated with the subsynaptic web of axosomatic synapses and these two cytoplasmic components display many structural similarities. In the light of these and previously reported observations, it would appear that nematosomes are not incidental cytoplasmic inclusions, but common organelles of certain types of neurons.
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    Cell & tissue research 125 (1972), S. 143-175 
    ISSN: 1432-0878
    Keywords: Skin ; Cephalopods ; Chromatophores ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Rapid, physiological color changes seen in the skin of cephalopods are due to a unique anatomical system composed of chromatophore organs and iridophores. The morphology and ultrastructure of the chromatophores was studied in the squids Loligo pealii Lesueur and Loligo opalescens Berry. A three-dimensional model of a brown chromatophore was reconstructed from serial sections for the electron microscope. The chromatophore organ is composed of a central nucleated pigment cell, 10–30 obliquely striated muscle cells (radially arranged on the equator of the pigment cell), axons, Schwann cells, and sheath cells. The pigment cell consists of a central aggregation of pigment granules and surrounding peripheral cytoplasmic compartments. These regions are incompletely separated by an electron-dense, sac-like structure, the pigment container. Proximal portions of a muscle cell contact the pigment cell in regions called myo-chromatophore junctions. Neuromuscular and myo-muscular junctions are also present. The results presented are discussed in terms of previous morphological and physiological studies of chromatophores.
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    Cell & tissue research 125 (1972), S. 176-190 
    ISSN: 1432-0878
    Keywords: Skin ; Cephalopods ; Iridophores ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Two populations of iridophores are responsible for the iridescent color of the squids Loligo pealii and Loligo opalescens. The superficial group, the short iridophores, underlie the chromatophores and are associated with muscle cells of the skin. The long iridophores, a deeper-lying group, are arranged in a dense sheet. The ultrastructure of iridophores was described, including iridosomes, iridosomal platelets and iridosomal tubules. The observations were discussed in terms of adaptive coloration in these animals.
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    Cell & tissue research 125 (1972), S. 210-228 
    ISSN: 1432-0878
    Keywords: Regio olfactoria ; Teleosts ; Anguilla anguilla ; Ultrastructure ; 3 Different receptor types
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Das Flimmerepithel von Anguilla anguilla besteht aus 4 Zellarten: Flimmerzellen, Stützzellen, Basalzellen und Schleimbecherzellen. Flimmerzellen enthalten im oberen Zelldrittel zahlreiche Mitochondrien und tragen an ihrer Oberfläche bis zu 140 Kinocilien. Die Basalkörper dieser Kinocilien haben lange Wurzelfilamente, von denen ein Teil ins Zellinnere zieht; der andere Teil verläuft parallel zur Oberfläche und verbindet benachbarte Basalapparate. — Ein Übergangsepithel verknüpft das Flimmerepithel mit dem Riechepithel. Im Riechepithel finden sich außer den Zellarten des Flimmerepithels die Rezeptoren. Bei einheitlichem Aufbau des Zellkörpers lassen sich aufgrund rein morphologischer Unterschiede der Vesiculae olfactoriae 3 Rezeptortypen unterscheiden: 1. Cilien-Rezeptor, 2. Mikrovilli-Rezeptor und 3. „Pfriem“-Rezeptor. — Der Cilien-Rezeptor trägt unterhalb der Vesicula olfactoria in einer Einschnürung 4–8 sensorische Cilien, die alle auf gleicher Höhe entspringen. Zwei gegenüberliegende sensorische Cilien schließen einen konstanten Winkel von 60° ein. — Der Mikrovilli-Rezeptor trägt auf seiner abgerundeten Vesicula olfactoria 30 bis 60 Mikrovilli von 0,1 μm Dicke und bis zu 5 μm Länge. Der Mikrovillus wird von einem zentralen, 160 Å weiten, Tubulus durchzogen. Unterhalb der Vesicula olfactoria liegen mehrere Centriolen. Die Rezeptornatur dieser Zellen wird durch ein Axon unterstrichen. — Der „Pfriem“-Rezeptor besitzt eine 0,8 μm breite und bis zu 4 μm lange Vesicula olfactoria ohne sensorische Cilien und ohne Mikrovilli. Im Lumen der Vesicula olfactoria befinden sich neben Neurotubuli auch Fibrillen von 40–50 Å Durchmesser, die gebündelt auftreten. An der Basis des Köpfchens liegen mehrere Centriolen.
    Notes: Summary The ciliary and olfactory epithelia of the olfactory folds in Anguilla anguilla were studied with the electron microscope. The ciliary epithelium is composed of ciliary cells, supporting cells, basal cells, and mucous cells. The ciliary cells contain numerous mitochondria in their apical portion and bear up to 140 cilia. The ciliary basal bodies have rootlets, some of which project towards the central part of the cell, and others parallel to the cell surface thereby connecting neighbouring basal bodies. A transitional epithelium is located between the ciliary and olfactory epithelia. The olfactory epithelium is composed of the same 4 cell types of the ciliary epithelium and besides contains three morphologically different receptor cell types: ciliary receptor cells, microvillous receptor cells, and receptors with a single rodshaped free appendage. The ciliary receptors have 4 to 8 “sensory” cilia which project from below the vesicula olfactoria, each forming a constant angle of about 30° with the vertical cell axis. The vesicula olfactoria of the microvillous receptors bears from 30 to 60 microvilli, each of 0.1 μm diameter and up to 5 μm length. Each microvillus of this receptor type contains a central tubulus of 160 Å diameter. Few centrioles are located closely to the vesicula olfactoria. The third receptor type, which has neither cilia nor microvilli, is characterised by a single rod-shaped appendage of 0.8 μm diameter which projects up to 4 μm above the epithelial surface. This appendage contains neurotubules and fibril bundles; some centrioles lie close to the base of the appendage.
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    Cell & tissue research 125 (1972), S. 277-288 
    ISSN: 1432-0878
    Keywords: Neurohypophysis ; Rat ; Exocytosis ; Freeze-etching ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Neural lobes of rats subjected to severe acute haemorrhage under sodium pentobarbitone anaesthesia were examined electron microscopically and the ultrastructure compared with that in anaesthetised and unanaesthetised controls. Changes in the localisation and numerical distribution of elementary granules and small vesicles in the neurohypophysial nerve endings of bled rats were consistent with the occurrence of exocytosis. The occurrence of “exocytotic profiles” was observed more frequently in freeze-etched tissue samples as compared with the material fixed for conventional electron microscopy. The ratio of small vesicles: elementary granules was shown to be significantly increased (P〈0.005) in the nerve endings of neural lobes from bled rats. Equally, the numbers of exocytotic profiles related to 1000 μm2 of neurohypophysial tissue area were significantly greater (P〈0.005) in bled rats.
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    Cell & tissue research 125 (1972), S. 252-276 
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    Keywords: Amnion-Umbilical-cord-Skin ; Sheep ; Differentiation of the epithelia ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die Ektoblastderivate Amnion-, Nabelstrang- und Hautepithel von 14 Schaffeten zwischen 1,1 und 44 cm SSL wurden elektronenmikroskopisch untersucht. Das Amnionepithel ähnelt dem anderer Säuger; die tonofibrillenreichen Zellen sind mit Mikrovilli besetzt, seitlich sind sie stark miteinander verzapft. Das Schlußleistennetz bleibt bis zur Geburt erhalten. Der Golgiapparat ist kräftig entwickelt. Glatte Mikropinozytosevesikel von 600–800 Å Ø am basalen und seitlichen Plasmalemm werden mit fortschreitender Entwicklung zahlreicher. Größere Vakuolen fehlen. Das Nabelstrangepithel bleibt im Gegensatz zu anderen Spezies ein geringfügig modifiziertes Amnionepithel ohne eigene Differenzierung. In der zweiten Trächtigkeitshälfte sind die Interzellularräume durchschnittlich weiter als im peripheren Amnionepithel. Mikropinozytosebläschen kommen auch an apikalen Mikrovilli vor. Die Epidermis ist schon im einschichtigen Stadium nicht amnionähnlich, die apikalen Mikrovilli sind wesentlich spärlicher und kürzer, die Interzellularräume sind oft einfacher geformt, basal finden sich bereits Hemidesmosomen. Bei größeren Feten werden die Interzellularräume sehr eng, die Mikrovilli stehen in Gruppen. Weder in den glykogenbeladenen Peridermzellen noch in den Basalzellen sind Pinozytosevesikel, Fruchtwasservakuolen oder andere Indizien für einen Fruchtwassertransport zu finden.
    Notes: Summary The ultrastructure of the derivates of the ectoblast, the epithelia of the amnion, umbilical cord and skin has been studied in fetal sheep ranging from 1.1 to 44 cm CRL. The amniotic epithelium is similar to that of other mammals. The cells are rich in tonofilaments, they carry microvilli and are interdigitated with one another. Terminal bars are retained until birth. The Golgi apparatus is well developed. Smooth micropinocytotic vesicles with a diameter of 600–800 Å on the basal and intercellular cell membranes become more numerous with progressing development. Larger vacuoles are missing. The epithelium of the umbilical cord, contrary to that of other species, remains a slightly modified amniotic epithelium without special differentiation. The intercellular spaces are on the average wider in the second half of pregnancy than those in the peripheral amniotic epithelium. Micropinocytotic vesicles occur also on the apical microvilli. In the single layer stage the epidermis is dissimilar to that of the amniotic epithelium. The apical microvilli are far less numerous and shorter, the intercellular spaces are often of a more simple structure. Hemidesmosomes occur in the basal cell membrane. Later the intercellular spaces become very narrow, the microvilli are present in clusters. Pinocytotic vesicles, amniotic fluid vacuoles or other indications of amniotic fluid transport are to be found neither in the glycogen-rich peridermal cells, nor in the basal cells.
    Type of Medium: Electronic Resource
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  • 92
    ISSN: 1432-0878
    Keywords: Hypophyse ; Quail ; Thyroidectomy ; Castration ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé On compare l'ultrastructure et la localisation des phosphatases acides au niveau des cellules hypophysaires delta et beta, chez des Cailles mâles thyroïdectomisées et maintenues en photopériode courte ou bien castrées, puis placées en photopériode longue. On étudie en outre, dans ces deux cas, les effets d'injections de doses croissantes de thyroxine. La thyroïdectomie provoque la transformation des cellules delta en cellules de thyroïdectomie groupées en îlots à la périphérie du lobe céphalique. Ces cellules sont pauvres en phosphatases acides. La thyroxine (10 μg/j pendant 2 jours) provoque la régression de ces cellules et l'apparition de lysosomes. Les cellules beta ne sont pas modifiées par la thyroïdectomie. La castration-photostimulation stimule les cellules beta localisées dans le lobe céphalique. Elle provoque dans les deux lobes de la glande l'hypertrophie et la vacuolisation des cellules delta qui se distinguent des cellules de thyroïdectomie par la présence de nombreux lysosomes. La thyroxine freine simultanément l'activation des cellules delta et des cellules beta, en provoquant la formation de lysosomes, mais la dose efficace chez le mâle photostimulé (20 μg et 60 μg/j pendant 5 jours) est sans effet chez le castrat photostimulé (dose efficace 180 μg/j). Pour interpréter ces faits, on admet que les cellules delta, thyréotropes et les cellules beta, gonadotropes, seraient simultanément soumises à un contrôle freinateur des hormones thyroïdiennes et des stéroïdes mâles.
    Notes: Summary The ultrastructure and the localization of acid-phosphatase activity are compared in beta and delta pituitary cells of male Japanese quail, either thyroidectomized and maintained in short days, or castrated then put in long days. Moreover, in these two cases, the effects of brief treatments with increasing doses of thyroxine are studied. Thyroidectomy induces transformation of delta cells into “thyroidectomy cells” arranged in clumps at the periphery of the cephalic lobe. The acid-phosphatase activity of such cells is low. Thyroxine (10 μg per day for two days) causes regression of these cells and the appearance of numerous lysosomes. Beta cells are not modified by thyroidectomy. Castration and exposure to long days stimulate beta cells, localized in the cephalic lobe. It induces, also, in both pituitary lobes, hypertrophy and vacuolization of delta cells which differ from thyroidectomy cells by the presence of numerous lysosomes. Thyroxine in photostimulated quail inhibits both delta- and beta-cell stimulation and increases the frequency of lysosomes but the effective doses on males (20 μg or 60 μg per day for five days) are inactive on castrates, the response of which is obtained with 180 μg per day. In order to explain these data, a hypothesis is suggested: Thyrotropic delta cells and gonadotropic beta cells are both subject to a double inhibiting control by thyroid hormones and male steroids.
    Type of Medium: Electronic Resource
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  • 93
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 123 (1972), S. 486-495 
    ISSN: 1432-0878
    Keywords: Pomatoceros triqueter ; Cytokinesis ; Surface folding ; New surface membrane ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The first cleavage division of Pomatoceros triqueter eggs is described. Time-lapse microcinematographic and electron microscopic studies revealed that, prior to division, the plasma membrane was folded into pleats. These were not present after division. This fact pointed to an unfolding of the plasma membrane which enabled it to cover the increased surface area resulting from cleavage. It is suggested that the pre-cleavage folds are derived from the membranes of the cortical granules, which continue releasing their contents into the perivitelline region following fertilization and first division. Filamentous material in the form of a band was present subjacent to the plasma membrane in the region of the furrow. The individual filaments of this band measure 5 to 7 nm in cross section, the dimensions being similar to those described for other kinds of dividing cells.
    Type of Medium: Electronic Resource
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  • 94
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 124 (1972), S. 39-43 
    ISSN: 1432-0878
    Keywords: Ruminal epithelium ; Zonulae occludentes ; Goat ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Das Pansenepithel besitzt in den tiefen Hornzellen, die an das Stratum granulosum grenzen, eine Barriere. Diese Barriere, die das Labyrinth der Interzellularräume gegen das Pansenlumen verschließt, ist mit Zonulae occludentes ausgestattet.
    Notes: Summary The deep horn cells of the goat ruminal epithelium, which border the stratum granulosum, form an important component of the epithelial barrier. This barrier of the intercellular labyrinth presents zonulae occludentes (tight junctions).
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  • 95
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 124 (1972), S. 311-319 
    ISSN: 1432-0878
    Keywords: Median eminence ; Rat ; Neurovascular contacts ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the median eminence of the rat axons of the supraoptic-paraventricular-hypophyseal tract with elementary neurosecretory granules (150–200 mμ) traverse the internal zone. Terminals containing dense core vesicles 60–120 mμ in diameter end on the portal capillaries of the median eminence. A unique organisation of the primary portal capillaries is shown. Endothelial cells have many fenestrae. The pericapillary space has numerous extensions all of which represent a special zone around the endothelial tube. The fine structural organisation and function of the neurovascular contacts in the median eminence are discussed.
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  • 96
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 124 (1972), S. 520-531 
    ISSN: 1432-0878
    Keywords: Mitochondria ; Cytomembranes ; Oocyte ; Pig ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An ultrastructural study of the mature follicular oocytes in domestic pig demonstrate a morphological relationship between the mitochondria and the cytoplasmic membranes immediately surrounding the yolk globules of the cells. Frequently, the cytoplasmic membranes are observed to be in close proximity of the mitochondria or are found to be continuous with the outer mitochondrial membrane. Sometimes the cytoplasmic membranes are found to display the formation of one or more oval loops of different diameter located at their presumed ends or free in the nearby cytoplasm. The significance of these observations is discussed in the light of the available informations, which suggest that the cytomembrane system in certain phases of development may take part in the formation of mitochondria.
    Type of Medium: Electronic Resource
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  • 97
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 126 (1972), S. 1-16 
    ISSN: 1432-0878
    Keywords: Oocyte ; Rana pipiens ; Ultrastructure ; Cytochemistry ; Enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In early diplotene frog oocytes incubated to illustrate thiamine pyrophosphatase (TPPase) activity, reaction product is uniformly distributed within the compartments of the endoplasmic reticulum and nuclear envelope as well as within the saccules and small vesicles comprising the dictyosomes. With continued oocyte development the reaction product becomes concentrated in localized regions of the dictyosome saccules. Eventually, the enzyme is no longer apparent within the endoplasmic reticulum, but is concentrated in the cisternae of the inner dictyosome saccules. The variations noted suggest that the enzyme is synthesized early in diplotene by the endoplasmic reticulum and is subsequently transported to the Golgi apparatus where it is consistently observed at later developmental stages. TPPase activity is also present in the Golgi apparatus of follicle and theca cells as well as in ovarian epithelial cells. The enzyme is also detected in micropinocytotic vesicles contained within the cells comprising the follicle envelope and in intercellular spaces of the follicle. Horseradish peroxidase injected into the coelomic cavity is transported via micropinocytotic vesicles into and through the cells comprising the follicle envelope and in intercellular spaces. The exogenous protein is not found even after a prolonged time period in early diplotene oocytes. The protein is, however, present in large spherical and “tubular” vesicles in the cortex of vitellogenic oocytes approximately 500 microns in diameter. The possible functional role of the enzyme TPPase during oogenesis is discussed.
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  • 98
    ISSN: 1432-0878
    Keywords: Epithelial cells ; Echinoderm ; Asterina gibbosa ; Regeneration ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé L'évolution ultrastructurale de la cellule neuroépithéliale a été faite, chez Asterina gibbosa, au cours de la régénération du bras. La dédifférenciation de la cellule, provoquée par l'amputation, se manifeste par la perte de sa partie apicale et la régression des structures cytoplasmiques: vésiculisation du Golgi et de l'ergastoplasme, fragmentation des microtubules. L'activation qui accompagne la dédifférenciation, se manifeste par la formation d'un nucléole au centre du noyau. Elle correspond à la reprise des synthèses d'ARN. La cellule dédifférenciée est caractérisée par un nucléole excentré et l'abondance des ribosomes libres. La différenciation débute par le regroupement en rosettes des ribosomes et le développement des canalicules ergastoplasmiques. Le Golgi réapparaît au voisinage du noyau. Les mitochondries se disposent aux pôles basal et apical de la cellule, où les microtubules se reconstitutent. En fin de différenciation, les cellules se réorganisent pour édifier un épithélium cicatriciel limité par une basale. Le tissu épidermique se différencie à partir des éléments de même origine sans l'intervention de cellules souches.
    Notes: Summary The ultrastructural differentiation of the neuroepithelial cell in the course of regeneration in Asterina gibbosa has been investigated up. Cell differentiation, induced by cutting the arm off, is characterized by loss of the apical cell pole and alteration of cytoplasmic structures: vesiculation of the Golgi apparatus and the ergastoplasm, fragmentation of microtubules. Activation, which parallels dedifferentiation, induces the appearance of a nucleolus in the center of the nucleus. This means that RNA synthesis is starting again. A dedifferentiated cell shows an eccentric nucleolus and many free ribosomes. Differentiation beginning, clusters of ribosomes and the development of tubular ergastoplasmic formations can be observed. The Golgi apparatus is located near the nucleus. Mitochondria gather at basal and apical part of the cell, where also microtubules are forming again. In the last stage of differentiation, cells are joining up and build a scar epithelium resting on a basement membrane. Epidermic tissue differentiates only from epidermic cells. Blast cells have no part in this process.
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  • 99
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 126 (1972), S. 446-453 
    ISSN: 1432-0878
    Keywords: Eye ; Manduca sexta ; Ommatidia ; Retinula ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The superposition eye of the sphingid moth, Manduca sexta was explored by means of the scanning electron microscope (SEM). Specifically examined were the corneal nipple array, corneal lens, crystalline cones and tracts, photoreceptor cells and their axons. Descriptions of the external ultrastructure of the components were correlated, where possible with previously published accounts of internal ultrastructure as obtained from TEM studies. A key finding was the demonstration of the axial rotation of the eccentrically situated retinular cell, its externally noted prominence and the arrangement of the other photoreceptor cells composing the retinula. Because of the interest in superposition eye theory, the functional significance of various preretinular optic components was reviewed where it specifically related to Manduca.
    Type of Medium: Electronic Resource
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  • 100
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 127 (1972), S. 323-346 
    ISSN: 1432-0878
    Keywords: Thymus ; Frog ; Development ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A study of the ultrastructure of the developing thymus of the leopard frog (Rana pipiens) revealed that the thymus had undergone all of the major changes which would persist through larval life and metamorphosis by the time that the animals had reached larval stage IV of Taylor and Kollros (1946). These changes included development of an outer, lymphoid cortical region and an inner, essentially nonlymphoid medulla; mitotic activity among lymphoid cell precursors and the formation of the first small lymphocytes; development of complex cysts containing PAS-positive material and the appearance of other signs of secretory activity among epithelial cells of the medulla; and differentiation of large myoid cells containing bundles of striated muscle fibrils. The changes are particularly noteworthy because they first appear during a period in which the animals are known to be developing the capacity to respond immunologically to allografts.
    Type of Medium: Electronic Resource
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