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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 186 (2000), S. 347-357 
    ISSN: 1432-1351
    Keywords: Key words Crustacean ; Sensorimotor ; Ultrastructure ; Multilamellar sheath ; Myelinated axons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Speed of nerve impulse conduction is greatly increased by myelin, a multi-layered membranous sheath surrounding axons. Myelinated axons are ubiquitous among the vertebrates, but relatively rare among invertebrates. Electron microscopy of calanoid copepods using rapid cryofixation techniques revealed the widespread presence of myelinated axons. Myelin sheaths of up to 60 layers were found around both sensory and motor axons of the first antenna and interneurons of the ventral nerve cord. Except at nodes, individual lamellae appeared to be continuous and circular, without seams, as opposed to the spiral structure of vertebrate and annelid myelin. The highly organized myelin was characterized by the complete exclusion of cytoplasm from the intracellular spaces of the cell generating it. In regions of compaction, extracytoplasmic space was also eliminated. Focal or fenestration nodes, rather than circumferential ones, were locally common. Myelin lamellae terminated in stepwise fashion at these nodes, appearing to fuse with the axolemma or adjacent myelin lamellae. As with vertebrate myelin, copepod sheaths are designed to minimize both resistive and capacitive current flow through the internodal membrane, greatly speeding nerve impulse conduction. Copepod myelin differs from that of any other group described, while sharing features of every group.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1437-773X
    Keywords: Key words Mitogen-activated protein kinase (MAPK) ; Ischemia reperfusion injury ; Heart ; Ultrastructure ; Immunohistochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The mitogen-activated protein kinase (MAPK) family is considered to be activated by stress, but the role of the MAPK family is still unknown in cardiac pathology. In the present study, not only the localization of MAPKs such as the extracellular responsive kinase (ERK), c-jun N-terminal kinase (JNK), and p38 MAPK (p38), but also ultrastructural changes were investigated in the ischemia-reperfusion model of Wistar rats. At 5, 10, 30, 60, and 180 min reperfusion after 30 min ischemia by occluding the coronary artery, the expression of these MAPKs was increased in blood vessels and cardiomyocytes by Western blotting and immunohistochemical methods. In addition, after ischemia reperfusion, various ultrastructural changes such as decreased glycogen granules, mitochondrial swelling, and myolysis were observed in the blood vessels and cardiomyocytes. These results suggest that protein kinases may regulate numerous biological processes, including the regulation of contraction and ion transport.
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  • 3
    ISSN: 1437-773X
    Keywords: Key words Gonadotroph adenoma ; FSH ; Childhood ; Ultrastructure ; Immunohistochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Female gonadotroph adenomas with endocrinological symptoms are uncommon. Six cases of such adenomas have been reported in the literature: two were girls who presented with precocious puberty and four were premenopausal women with accompanying multiple ovarian cysts. We describe here a 10-year-old Japanese girl with a gonadotroph macroadenoma and present detailed morphological findings of the tumor. The patient's chief complaints were nausea, abdominal distention, and abdominal pain. Abdominopelvic ultrasonography and magnetic resonance imaging (MRI) revealed bilateral multiple ovarian cysts. Endocrinological assays showed elevated serum follicle-stimulating hormone (FSH) (33.7 mIU/ml) and estradiol (3840 pg/ml). MRI of the head showed a large pituitary tumor. Two transsphenoidal operations and subsequent radiation therapy were performed. Immunohistochemically, more than half the tumor cells were positive for anti-FSH-β monoclonal antibody. Ultrastructurally, the tumor cells exhibited a fairly uniform picture of rounded cells. Their nuclei were slightly irregular and contained heterochromatin, and their cytoplasm contained many round, dense core granules, measuring 140–260 nm in diameter, together with well-developed organelles. An in vitro study showed that the tumor cells in primary culture produced FSH (1089.0 mIU/ml). To our knowledge, this is the first immunohistochemical and ultrastructural study of an FSH-secreting gonadotroph adenoma occurring in childhood.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1437-773X
    Keywords: Key words Apoptosis ; Helicobacter pylori ; Fibroblasts ; Smooth muscle cells ; Ultrastructure ; Gastroduodenal ulcer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract It has been considered that Helicobacter pylori (H. pylori) infection is a major cause of human gastritis and gastroduodenal ulcers (G-DU). Many investigations of the relationship between H. pylori and apoptosis have been reported recently. However, these studies focused mostly on epithelium, using the TUNEL method. In the present study, we evaluated by electron microscopy the occurrence of apoptosis in the mesenchymal cells of lamina propria mucosae infected with H. pylori. Gastric biopsy specimens from 37 H. pylori-infected G-DU patients and 8 noninfected volunteers were examined with both light and electron microscopy and analyzed by the TUNEL method. The TUNEL method showed no significant difference between H. pylori-infected and noninfected cases. In contrast, electron microscopy revealed significant numbers of apototic fibroblasts and smooth muscle cells in H. pylori-infected lamina propria mucosae, with a diminished number of collagen fibers in surrounding areas. These areas showed edematous changes histopathologically. These results indicated that H. pylori infection induces apoptosis of fibroblasts and smooth muscle cells in lamina propria, with decrease in the numbers of collagen fibers, suggesting that these alterations may be affected by exaggerate acid secretion, decrease mucus protecting factors, and result in ulcer formation.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Medical electron microscopy 33 (2000), S. 109-114 
    ISSN: 1437-773X
    Keywords: Key words Ciliogenesis ; Ciliated cell ; Abnormal cilia ; Basal body ; Ultrastructure ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cilia are motile processes extending from the basal bodies, playing important roles in the mucociliary clearance in the respiratory tract and the transport of the ovum from the ovary to the uterus in mammals. Ciliogenesis is divided into four stages: (1) duplication of centrioles; (2) migration of centrioles to the apical cell surface to become basal bodies; (3) elongation of cilia containing the axoneme; and (4) formation of accessory structures of basal bodies. The orderly course of ciliogenesis appears to be disturbed by various internal and external factors and, as a result, various unusual forms of the ciliary apparatus develop in the cell. Inhibition of basal body migration results in development of intracytoplasmic axonemes, cilia within periciliary sheaths, and intracellular ciliated cysts. Swollen cilia and the bulging type of compound cilia are formed during ciliary budding and elongation. This review also discusses the origin, composition, and function of the centriolar precursor structures.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Medical electron microscopy 33 (2000), S. 135-142 
    ISSN: 1437-773X
    Keywords: Key words Elastic system fiber ; Ultrastructure ; Fibrotic human liver ; Oxytalan fiber ; Elaunin fiber
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The network of elastic system fibers in human fibrotic liver was investigated by histological methods, immunohistochemical staining, and electron microscopy. Type III collagen was seen not only in regions of portal fibrosis but also in the sinusoidal wall. However, elastic system fibers were not found in the Disse space of the sinusoidal wall. Elastic system fibers including oxytalan, elaunin, and elastic fibers were found successively in the course of elastogenesis. A few normal oxytalan fibers and abnormal oxytalan fibers were observed in the periportal tracts. Few normal elaunin and abnormal elaunin fibers were observed in regions of portal fibrosis but not in the surrounding margin. Elastic fibers, only in scarce amounts, were observed around the portal veins in the case of chronic active hepatitis but not in acute hepatitis. Abnormal oxytalan fibers were seen as a bundle of wavelike microfibrils and had an irregular arrangement. Abnormal elaunin fibers were not associated with bundles of microfibrils. Abnormal elaunin fibers in large amounts were found interspersed with spiraled collagen, which most likely indicates that the oxytalan fibers degenerated in the course of elastogenesis. Thus, in a fibrotic liver it is possible that synthesis of normal elaunin and elastic fibers does not occur or that the quantity of such fibers synthesized may be small because of the effect of the degenerated oxytalan fibers. As a characteristic of liver fibrosis, the composition of abnormal elastic system fibers and spiraled collagen differs from that in other fibrotic organs.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1437-773X
    Keywords: Key words Adenoid basal carcinoma ; Uterine cervix ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Adenoid basal carcinoma of the uterine cervix is a rare tumor with a favorable prognosis. A case of adenoid basal carcinoma (ABC) of the uterine cervix was studied using light and electron microscopy. The patient was a 74-year-old Japanese woman who had undergone hysterectomy due to cervical intraepithelial neoplasia 3. Incidentally, ABC was found in the resected uterus. The tumor cells made small nests and infiltrated the cervical portion of the uterus. In the nests, glands, cribriform patterns with glandlike structures, and squamous differentiation were seen. Immunohistochemically, the glandlike structures were positive for laminin and type IV collagen. Ultrastructurally, the tumor cells had irregular nuclei, scanty cytoplasm, and cribriform patterns in which glandlike structures were covered with basal lamina. No myoepithelial differentiation of the tumor cells was seen. These findings suggest a similarity between adenoid basal carcinomas and adenoid cystic carcinomas. Furthermore, both tumors are considered to originate in the reserve cells of the uterine cervix. Because their outcomes are different, they should be distinguished from each other.
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  • 8
    ISSN: 1432-2161
    Keywords: Key words Giant rice body ; Ultrastructure ; Immunohistochemistry ; Histogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Objective: To report four cases of rice bodies (RBs) showing remarkable size variations and discuss their pathogenesis. Design and patients: Based on analysis of the clinical data, we speculate on the pathogenesis of RBs using immunohistochemical and ultrastructural methods. The patients comprised three men and one woman, three with RBs in the subacromial bursae and one in the wrist synovial sheath, aged 28 (woman), 44, 50 and 81 (wrist) years, respectively. Results: There were no particular differences in clinical data among the patients. T2-weighted MR imaging was very useful for diagnosis of the RBs, allowing their clear delineation from the bursal fluid. The RBs consisted of a layered protein- aceous substance with vague targetoid cut surfaces. Much fibrin and a lesser amount of collagen fibers were recognized together with various mononuclear cells, which were few in number and predominantly T cells. The bursae and synovial sheath had multiple fibrinoid spheroids at the luminal surface. Conclusion: Fibrinoid nodular deposits probably became detached, forming the nuclei of RBs and growing to a giant RB 65 mm in diameter.
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  • 9
    ISSN: 1432-2307
    Keywords: Key words Arteriogenesis ; Collateral vessels ; Ultrastructure ; Cell adhesion molecules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Previous studies in the canine heart had shown that the growth of collateral arteries occurs via proliferative enlargement of pre-existing arteriolar connections (arteriogenesis). In the present study, we investigated the ultrastructure and molecular histology of growing and remodeling collateral arteries that develop after femoral artery occlusion in rabbits as a function of time from 2 h to 240 days after occlusion. Pre-existent arteriolar collaterals had a diameter of about 50 µm. They consisted of one to two layers of smooth muscle cells (SMCs) and were morphologically indistinguishable from normal arterioles. The stages of arteriogenesis consisted of arteriolar thinning, followed by transformation of SMCs from the contractile- into the proliferative- and synthetic phenotype. Endothelial cells (ECs) and SMCs proliferated, and SMCs migrated and formed a neo-intima. Intercellular adhesion molecule (ICAM-1) and vascular cell adhesion molecule (VCAM-1) showed early upregulation in ECs, which was accompanied by accumulation of blood-derived macrophages. Mitosis of ECs and SMCs started about 24 h after occlusion, whereas adhesion molecule expression and monocyte adhesion occurred as early as 12 h after occlusion, suggesting a role of monocytes in vascular cell proliferation. Treatment of rabbits with the pro-inflammatory cytokine MCP-1 increased monocyte adhesion and accelerated vascular remodeling. In vitro shear-stress experiments in cultured ECs revealed an increased phosphorylation of the focal contacts after 30 min and induction of ICAM-1 and VCAM-1 expression between 2 h and 6 h after shear onset, suggesting that shear stress may be the initiating event. We conclude that the process of arteriogenesis, which leads to the positive remodeling of an arteriole into an artery up to 12 times its original size, can be modified by modulators of inflammation.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 99 (2000), S. 310-316 
    ISSN: 1432-0533
    Keywords: Key words Ganglioglioma ; Ependymoma (tanycytic variant) ; Neurofibrillary tangle ; Immunohistochemistry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We studied a cystic ganglioglioma (GG) located in the right frontal lobe of the brain. Interestingly, the fibrillary spindle glial cells were often arranged in a fascicular pattern, and the generally uniform, round-to-oval delicate nuclei appeared to resemble those of ependymoma; and the neoplastic neurons often contained neurofibrillary tangles (NFTs). The glial component was positive for glial fibrillary acidic protein and occasionally contained granular or microvesicular structures positive for epithelial membrane antigen. Ultrastructural investigation revealed that the glial cells were ependymal in nature; intracytoplasmic lumina and intercellular microrosettes lined with cilia and microvilli, as well as long zonulae adherentes, were evident. In addition, chromogranin A-positive granular staining, neurosecretory-granule-like structures, and parallel arrays of microtubules were sometimes associated with the blood vessels. We considered the present case to be an unusual example of GG with an ependymoma, more precisely a tanycytic ependymoma, as the glial component; to our knowledge, the existence of ependymoma as the main glial component of this particular tumor has not been described before. The occurrence of NFTs, which has been reported in several cases of GG, was an additional, unusual feature.
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 99 (2000), S. 214-218 
    ISSN: 1432-0533
    Keywords: Key words Eosinophilic inclusion body ; Inclusion ¶body ; Ependymoma ; Microlumina ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A study was undertaken to determine the pathological significance of previously unrecognized intracytoplasmic eosinophilic inclusions (IEIs) in ependymoma. The study group consisted of 58 ependymomas, all of which were pathologically characterized and graded according to the 1993 WHO classification. Electron microscopic studies were performed in 16 cases. The study showed that 33 (57%) ependymomas had IEIs and that in 8 cases these were abundant. Round and eosinophilic, their sizes varied from 10 μm to a tiny dot. Similar eosinophilic bodies were also observed between tumor cells. The inclusions were weakly PAS positive. On immunostains, IEIs were frequently positive for glial fibrillary acidic protein, less often for S-100 protein, and for epithelial membrane protein and CAM 5.2. They were negative for AE1/AE3, carcinoembryonic antigen and Ber-EP4. Ultrastructurally, IEIs represented intracytoplasmic lumens containing microvilli and cilia. These microlumina also frequently contained granulo-tubular materials. With reference to tumor subtypes, IEIs occurred most frequently in ordinary and clear cell ependymomas. IEIs were also present in 4 of 6 anaplastic ependymomas studied. In conclusion, IEIs represent microlumina and occur in more than a half of ependymomas including malignant examples. Their finding is a helpful diagnostic feature of ependymoma.
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 201 (2000), S. 51-61 
    ISSN: 1432-0568
    Keywords: Key words Female prostate (Skene gland) ; Ultrastructure ; Secretory (luminal) cells ; Basal (reserve) cells ; Intermediary cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The predominant cells of female prostatic glands lining their lumen were found to be tall cylindrical secretory cells with short stubby microvilli, protuberances of the apical cytoplasm, and with bleb formation. Abundant secretory vacuoles and granules, rough endoplasmic reticulum, developed Golgi complexes and numerous mitochondria are characteristic of their active secretory configuration with apocrine (apical blebs) and merocrine (secretory vacuoles and granules) type of secretion. Basal (reserve) cells were seen to be located between the secretory (luminal) cells and the basement membrane. Their ground cytoplasm is dense with rough endoplasmic reticulum and mitochondria. Their nuclei, unlike those of secretory cells, possess more peripheral condensed chromatin, denser dispersed chromatin and sporadic nucleoli. Besides the two basic types of mature prostatic cells intermediary cells were also seen, located between the basal and secretory cells or in their close vicinity. Their cytoplasm exhibits numerous profiles of rough endoplasmic reticulum and free ribosomes. Secretory vacuoles and granules were mostly practically absent (type 1 intermediary cells) so that they resembled basal (reserve) cells. In some of them, however, as in secretory cells, such secretory elements do gradually appear (type 2 intermediary cells). The finding of intermediary cells in the lining of prostatic glands supports the role of basal (reserve) cells in the renewal of cells in glands of the female prostate. The first ultrastructural analysis of the normal female prostate performed by transmission electron microscopy showed that, as in the postpubertal male, the prostatic glands in the adult female display mature secretory and basal cells. The results of the presented study further corroborate the contemporary concept of the female prostate as a functional genitourinary organ.
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  • 13
    ISSN: 1432-0533
    Keywords: Key words Alzheimer disease ; Fibrillar amyloid-β ; Astrocytes ; Microglial cell ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Ultrastructural three-dimensional reconstruction of human classical plaques in different stages of development shows that microglial cells are the major factor driving plaque formation by fibrillar amyloid-β (Aβ) deposition. The amount of fibrillar Aβ released by microglial cells and the area of direct contact between amyloid and neuron determine the extent of dystrophic changes in neuronal processes and synapses. The volume of hypertrophic astrocytic processes separating fibrillar amyloid from neuron is a measure of the protective activation of astrocytes. On the bases of the volume of amyloid star, microglial cells, dystrophic neurites, and hypertrophic astrocytic processes, and spatial relationships between plaque components, three stages in classical plaque development have been distinguished: early, mature, and late. In early plaque, the leading pathology is fibrillar Aβ deposition by microglial cells with amyloid star formation. The mature plaque is characterized by a balance between amyloid production, neuronal dystrophy, and astrocyte hypertrophy. In late classical plaque, microglial cells retract and expose neuropil on direct contact with amyloid star, enhancing both dystrophic changes in neurons and hypertrophic changes in astrocytes. In late plaques, activation of astrocytes predominates. They degrade amyloid star and peripheral amyloid wisps. The effect of these changes is classical plaque degradation to fibrillar primitive and finally to nonfibrillar, diffuse-like plaques.
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  • 14
    ISSN: 1432-0533
    Keywords: Key words GM1-gangliosidosis ; Ultrastructure ; Electrospray ionisation tandem mass spectrometry ; Diagnosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The post-mortem diagnosis of lysosomal storage diseases can be confounded by the unavailability of suitable material. Here we report the diagnosis of GM1-gangliosidosis in a cross-bred dog, from which only formalin-fixed brain was available, by a combination of electron microscopy and the detection of elevated levels of GM1-ganglioside within the tissue using the novel technique of electrospray ionisation tandem mass spectrometry. Electron microscopic examination of ultrathin sections of resin-embedded tissue revealed cytoplasmic inclusions (membranous cytoplasmic and zebra bodies) in brain stem and cerebellar neurons that were characteristic of a gangliosidosis. Glycolipids were extracted from the fixed tissue and analysed by tandem mass spectrometry. Two major ions were detected, which corresponded to GM1 (d18:1–C18:0) and GM1 (d20:1–C18:0). Their identity was confirmed by comparison of their fragmentation patterns with those of authentic standards. The concentration of GM1 was approximately sixfold higher on a wet weight basis than in the brain of a normal control dog, confirming the diagnosis of GM1-gangliosidosis.
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Virchows Archiv 436 (2000), S. 249-256 
    ISSN: 1432-2307
    Keywords: Key words Endothelial cells ; Cell culture ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The aim of the present work was to examine and compare the ultrastructure of bovine retinal endothelial cells (BRECs) in vitro during several passages in a medium selective for endothelial cells. The identity of the endothelial cells was confirmed immunohistochemically, up to the tenth passage. Changes in their ultrastructure in comparison to endothelial cells in vivo occurred at the onset of culturing and not progressively with repeated passages. The cultured BRECs show high metabolic activity in all passages. While retaining their identity as endothelial cells, they modify their lipid metabolism, so that lipids are stored. This change in lipid metabolism was induced by the medium.
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  • 16
    ISSN: 1432-2013
    Keywords: Key words Pineal organ ; Photoreceptor cells ; Ultrastructure ; Proteus anguinus ; Regressive evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We studied ultrastructure of the photoreceptor cells in the pineal organ of blind, depigmented, neotenic cave salamander, Proteus anguinus. Unlike in epigean vertebrates the outer segments of most photoreceptor cells consists of concentrically arranged lamellae, however; in few cells, the outer segments contain 7-9 plasma membrane disks. In both types of photoreceptor cells the outer segments enclose lumps of vesicles of different sizes. The photoreceptor cells of Proteus anguinus are similar to those in other cavernicolous fish species.
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  • 17
    ISSN: 1439-7609
    Keywords: Key words Septic arthritis ; Surface antigens ; Ultrastructure ; Burkholderia pseudomallei ; IEM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Burkholderia pseudomallei is the causative agent of melioidosis, a disease that frequently runs a protracted course and is very difficult to eradicate. The mechanisms that this organism uses to escape from host defense mechanisms and antibiotics are not well understood. The aim of the study was to compare the morphological characteristics and surface antigen expression of B. pseudomallei in naturally infected human synovial tissues with the characteristics of bacteria grown in culture media. Immunoelectron microscopic study was performed in four synovial biopsies taken from four B. pseudomallei septic arthritis patients. Colonies of pathogenic B. pseudomallei collected from culture media were used as positive controls. Polyclonal antibody to whole cell B. pseudomallei was used as a primary antibody. Complete bacteria-like particles were demonstrated both extracellularly and intracellularly in all four synovial specimens. The intracytoplasmic location of B. pseudomallei and mononuclear phagosome containing microcolony-like structures were demonstrated. B. pseudomallei found in the synovial membrane samples were mostly atypical, with fewer cytoplasmic electron lucent granules. Immunogold staining of bacterial surface antigens was weaker than staining of positive controls. We demonstrated atypical forms of B. pseudomallei and evidence for suppression of its surface antigens in naturally infected human synovial tissues. This adaptation may help bacteria to survive despite host immune surveillance and treatment with antibiotics.
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Mycorrhiza 10 (2000), S. 15-21 
    ISSN: 1432-1890
    Keywords: Anthoceros punctatus ; Arbuscular mycorrhiza ; Bryophytes ; Glomus ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Glomus claroideum (Schenck & Smith emend. Walker & Vestberg) were investigated for ability to form arbuscular mycorrhiza-like symbioses with the hornwort Anthoceros punctatus (L.). Spores were transferred to a cellulose acetate filter on water agar and a small portion of an Anthoceros thallus was placed directly upon the spores. Light-microscope observations 20 days after inoculation revealed branched hyphae growing within the thallus. After 45 days, arbuscules and vesicles were studied by light- and electron-microscopy. After 60 days in water agar culture, the colonised Anthoceros thalli were transferred to a low-nutrient medium agar. Hyphae spread in the agar and newly formed spores were observed 5 weeks after the transfer. After 4 months, about 1000 spores were formed in each Petri dish. This is the first report of an experimentally established arbuscular mycorrhiza-like symbiosis between an identified fungus belonging to the Glomales and a bryophyte.
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  • 19
    ISSN: 1432-5233
    Keywords: Key words Streptozotocin ; Diabetes ; Ventricular myocyte ; Cardiac muscle ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Contractile dysfunctions have been demonstrated in different experimental models of diabetes which have similar characteristics to many of the abnormalities found in the clinical setting. Administration of streptozotocin (STZ) to young adult rats induces β-cell necrosis of the pancreas which gives rise to hypoinsulinaemia and hyperglycaemia, features which are also seen in untreated type 1 clinical diabetes. We have investigated the chronic effects of STZ-induced diabetes on contraction in rat ventricular myocytes and ultrastructure of cardiac muscle. Diabetes was induced in male Wistar rats (230–270 g) with a single injection of STZ (60 mg kg−1). At 2 and 10 months after STZ treatment, the amplitude of contraction was larger in diabetic compared to control myocytes. Time to peak contraction was significantly longer at 2 months but appeared to normalise at 10 months after STZ treatment. In contrast, time to half relaxation of contraction was not significantly different after 2 months but was significantly reduced at 10 months after STZ treatment compared to control. Transmission electron microscope examination of cardiac muscle showed that the ultrastructure of cardiac muscle, especially structures associated with contraction, were not greatly altered after STZ treatment. Sarcomere lengths were not significantly different in papillary or ventricular muscle at 4 or 8 months after STZ treatment compared to control. Our data provide evidence that morphological defects in contractile myofilaments and associated structures cannot explain contractile dysfunctions seen in ventricular myocytes from STZ-treated animals.
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  • 20
    ISSN: 1615-6102
    Keywords: Arabidopsis thaliana ; Cryopreservation ; Dehydration ; Thermal analysis ; Sucrose ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Arabidopsis thaliana suspension cells were preserved in liquid nitrogen for over three years, using embedding of cells in calcium-alginate prior to subculture in sucrose-enriched medium, air-drying, and direct quenching in liquid nitrogen. Survival of cells reached 34%, yielding regrowth at the surface of all cryopreserved beads in less than 7 days. Following pretreatment and dehydration, the water content dropped from 2300% to 34% with respect to dry weight. Differential scanning calorimetry showed that glass transition occurred on cooling, followed by a slight crystallization event on rewarming. The survival of cells was independent of the cooling rate. The tolerance of the acute dehydration step increased progressively with sucrose pretreatment duration, indicating the requirement for adaptative cellular alterations. Ultrastructural studies revealed several changes in cells after sucrose pretreatment prolonged from 1 to 7 days: reversal of the initially plasmolyzed state, microvacuolation, numerous autophagic structures, scarcity of ribosomes, increase in number and size of starch grains. No cell division seemed to occur during this period. After air-drying and after a freeze-thaw cycle, followed by 24 h rehydration, regenerating cells had recovered a high level of ultrastructural organization and contained numerous polysomes suggesting an intense metabolic activity. Trehalose, a cryoprotective disaccharide not considered to be a metabolic substrate, yielded only 70% regrowth after freezing. Biochemical analysis showed that soluble sugars accumulated during the pretreatment, essentially sucrose or trehalose; the monosaccharide content also increased. In the light of these results, the action of sucrose in inducing freezing tolerance is discussed.
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  • 21
    ISSN: 1615-6102
    Keywords: Beta vulgaris ; Cyst nematodes ; Histology ; Resistance mechanism ; Syncytium ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Using susceptible and resistant sugar beet lines, comparative analyses of root histology and ultrastructure were made during invasion by nematodes and the induction and formation of specific feeding structures (syncytia).The resistant line carried the resistance geneHs1pro−1.Nematodes were able to invade and induce functional syncytia in roots of resistant and susceptible lines. However, syncytia in resistant roots were smaller and less hypertrophied. The vacuolar system of syncytia in susceptible plants contained many small vacuoles. In resistant plants vacuoles were larger but less numerous. Smooth endoplasmic reticulum prevailed in syncytial protoplasts of susceptible plants, whereas almost only rough endoplasmic reticulum occurred in syncytia in resistant plants. The most conspicuous and hitherto undescribed trait of syncytia in resistant roots was the initial appearance of loose, and later compact, aggregations of the endomembrane system which composed most of the endoplasmicreticulum system of syncytia at later stages. Syncytia in resistant plants usually degraded before the nematodes reached their adult stage. The appearance of membrane aggregations and the other resistance-specific features are discussed in relation to their possible effects on syncytium function and role in nematode resistance.
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  • 22
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    Protoplasma 211 (2000), S. 94-102 
    ISSN: 1615-6102
    Keywords: Androgenesis ; Embryogenesis ; Microspore culture ; Pollen ; Ultrastructure ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have made a detailed cytological examination of the development of wheat embryoids, monitoring their initial divisions from two to ten cells by both light and electron microscopy. According to our observations the first embryogenic division is symmetrical. After the androgenesis induction treatment, there is a decrease in ribosome population with cells that have inactive nucleoli made up almost exclusively of a dense fibrillar component. This population is restored after initial embryogenic divisions. During the initial divisions the embryogenic pollen grains do not appear to change in size and the pollen wall remains intact. The exine undergoes no modification but the intine thickens, and we have observed that the thickness of the intine can be used as a cytological marker of androgenesis. The walls separating the cells obtained after embryogenic division contained numerous plasmodesmata. The beginnings of embryo polarization and cell differentiation could be made out in the very early pollen embryoids.
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  • 23
    ISSN: 1615-6102
    Keywords: Glutathione ; Root ; Chromosomal aberration ; Ultrastructure ; Picea abies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Young spruce seedlings (Picea abies [L.] Karst.) grown in hydroponic culture were exposed to three different concentrations (50,100, and 500 μM) of reduced glutathione for 24 h. These physiologically relevant concentrations of glutathione had a multiple effect on the investigated tissue. Feeding of glutathione to roots increased the concentrations of thiols (glutathione, cysteine, and γ-glutamyl-cysteine) in roots, decreased the rate of cell divisions, induced mitotic abnormalities, and affected the cell ultrastructure. Electron micrographs showed effects such as advanced vacuolation, dilated rough-endoplasmic-reticulum cisternae, and separations of the plasma membrane from the cell wall.
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  • 24
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    Neurological sciences 21 (2000), S. S27 
    ISSN: 1590-3478
    Keywords: Key words Neuronal ceroid lipofuscinoses ; Lipopigments ; Ultrastructure ; Classification ; Genes ; Neuronal loss
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Morphological aspects of the neuronal ceroid lipofuscinoses (NCL) encompass two main features: loss of nerve cells and accumulation of autofluorescent lipopigments within cellular compartments. The former requires histology and morphometry for assessment, while the latter necessitates fluorescence microscopy, electron microscopy, and immunohistochemistry. Accumulation of lipopigments is widespread throughout the central nervous system and extracerebrally. The latter feature enables diagnosis of NCL and its clinical subtype. Loss of neurons is most pronounced in cerebral and cerebellar cortices, in early childhood forms. In subcortical grey matter and in later-onset forms, juvenile and adult NCL, reduction in neurons and possible preceding dendritic pathology may only correctly be ascertained by age-matched, controlled morphometric investigations which, to date, have not yet completely assessed subcortical neuronal damage. Presently, clinical and morphological evaluations are mandatory for genetic analysis, genetic counselling, and prenatal diagnosis, the latter often being based on combined genetic and morphological studies.
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  • 25
    ISSN: 1861-387X
    Keywords: Hemangioblastoma ; Supratentorial tumor ; Immunohistochemistry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Supratentorial hemangioblastomas are rarely seen, especially in children and adolescents. We report the case of a 17-year-old male with supratentorial hemangioblastoma. Neuroimaging demonstrated a cystic lesion within the right parietal lobe. Systemic examination revealed no abnormality. The lesion was not attached to the dura and was not associated with von Hippel-Lindau disease. It was very difficult to confirm the final diagnosis of this case, in spite of extensive examination by light microscopy, immunohistochemical studies, and electron microscopy.
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  • 26
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    Archives of gynecology and obstetrics 240 (1987), S. 33-43 
    ISSN: 1432-0711
    Keywords: Ovary ; Surface epithelium ; Perfusion ; Rabbit ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Using transmission electron microscopy we examined the morphology of the surface epithelium of the isolated and perfused rabbit ovary after an ovulatory dose of HCG. Rupture of follicles occurred in vitro approximately 13 h after HCG-injection and 6 h after the start of perfusion. The ultrastructural changes during the perfusion were similar to those occurring in vivo. The perfused ovarian epithelium had villous processes of varied architectural complexity with squamoid and cuboid epithelial cells. The superficial cells contained pinocytotic vesicles, coated and noncoated endocytotic caveolae, and occasional vacuoles. Dense bodies were more commonly found in vitro than in vivo. Occasionally structures similar to “Call-Exner-bodies” were found on the surface epithelium near to preovulatory follicles. Intercellular spaces of various sizes were also numerous. Disappearance of surface epithelium in the apex of follicles was often observed and the matrix of the tunica albuginea consisted of dissociated fibers and degenerating cells. This study showed that the isolated perfused rabbit ovary can serve as a model for studying the biology and pathology of ovarian surface epithelium.
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  • 27
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    Archives of gynecology and obstetrics 240 (1987), S. 137-146 
    ISSN: 1432-0711
    Keywords: Preovulatory granulosa cells ; Call-Exner body ; Fibrin ; Human ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ultrastructure of preovulatory granulosa cells may be distinct in follicles containing competent as opposed to non-competent oocytes. To test this assumption, granulosa cells were looked for in 36 follicular fluid aspirates from 8 patients taking part in an in vitro fertilization and embryo transfer program. Granulosa cells were absent from 16 aspirates and present in 20. Both aspirate types contained oocytes able to develop in culture. Granulosa cells were subdivided into three developmental stages. Stage 1 (5% of aspirates) showed proliferating cells, while stage 2 (60% of aspirates) and 3 (35% of aspirates) cells were in the preluteinization stage. These cells were recognizable by their number of lipid droplets and differentiated according to possession of a rough (stage 2) or smooth (stage 3) endoplasmic reticulum. Luteinization did not occur in these cells. All stages displayed desmosomes, gap junctions, and annular junctions. The structure of Call-Exner bodies and of fibrin deposits were unexpected findings. Our study indicates that there is no correlation between the previously used morphological parameters of granulosa cells and oocyte maturity.
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  • 28
    ISSN: 1432-2285
    Keywords: Cambial activity ; Frost hardiness ; Phenology ; Salix ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The ultrastructure of cells in the cambial region of Salix dasyclados Wim. (clone 78056) was studied during the development of winter hardiness and the onset of cambial activity in spring. Plants were grown at relative growth rates (RG) of 8% and 12% respectively, resulting in different nitrogen content in the stems. Frost hardiness of the plants was estimated by standardized freezing tests. Plants with a higher nitrogen status ceased growth later and started re-growth earlier in spring than plants with lower nitrogen content. Differences in ability to withstand low temperatures during autumn and spring were found between plants grown in the two nutrient treatments. During the development of frost hardiness in the autumn, the number of meristematic cells in the cambial region decreased. The cessation of meristematic activity was accompanied by cell wall thickening and ultrastructural changes in the cells. Frost hardiness increased from the ability to survive -6° C in October to survival of -80° C at the beginning of December. From November to February the cambial region comprised a layer of 2–3 thick-walled cells with conspicuous ultrastructural features. Starch accumulated in plastids in September, decreased during November to March and then increased again in accordance with changes of frost hardiness. Onset of cambial activity began between the end of March and the beginning of April, as shown by increased vacuolization of meristematic cells and mitotic activity. By April, the starch content had increased and lipolysis was observed. Frost hardiness had decreased, and plants with low and high nitrogen content were able to survive -15° C and -10° C, respectively. After budburst, all axillary shoot parts were damaged at temperatures below-3° C.
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  • 29
    ISSN: 1432-2307
    Keywords: Soft tissue neoplasm ; Sarcoma ; Rhabdoid cell ; Rhabdoid tumor ; Ultrastructure ; Immunohistochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We report the occurrence of rhabdoid cells in several specified soft tissue sarcomas of round cell variety. The rhabdoid cells had an acidophilic cytoplasm containing a globular perinuclear inclusion and were characterised ultrastructurally by the presence of aggregates of 10 nm intermediate filaments. These filaments contained both cytokeratin and vimentin, as demonstrated immunohistochemically. Extensive sampling of soft tissue sarcomas revealed the presence of such cells in different types of soft tissue round cell sarcomas as follows: 12 of 13 cases of epithelioid sarcomas, 8 of 13 synovial sarcomas (composed predominantly of round cells), 6 of 20 extraskeletal myxoid chondrosarcomas and 4 of 4 round celled malignant mesotheliomas. We wish to stress that the appearance of rhabdoid cells is not a monopoly of one particular type of tumour.
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  • 30
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    Virchows Archiv 412 (1987), S. 175-182 
    ISSN: 1432-2307
    Keywords: Appendix ; Colorectal neoplasm ; Carcinoid ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The clinicopathological features of six appendix and five bowel tumours with features of the so-called ‘goblet cell carcinoid’ are described. By light microscopy, these tumours were composed predominantly of mucous cells, together with variable proportions of endocrine and Paneth cells. Immunohistochemical and ultrastructural study confirmed this impression and no amphicrine cells were seen. The clinical course of all cases arising in the bowel, and three out of six appendix tumours was characterised by an aggressive behaviour with the development of widespread lymphatic and often intraperitoneal metastasis, but liver metastasis occurred in only one instance. We conclude, both from this study and from a review of the literature, that the ‘mixed crypt cell carcinoma’ forms a distinct clinicopathological entity justifying separate classification from adenocarcinoma and carcinoid tumour.
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  • 31
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    Virchows Archiv 411 (1987), S. 93-98 
    ISSN: 1432-2307
    Keywords: Gliomatosis cerebri ; Brain tumour ; Ultrastructure ; Glial cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ultrastructural features of five biopsies of gliomatosis cerebri (GC) are described. Four main types of tumour cells are seen: anaplastic astrocytes poor in organelles with a variable amount of glial microfilaments; atypical oligodendrocytes with scanty cytoplasm in which microtubules are present; intermediate forms with aboundant cytoplasm rich in organelles, with microtubules and microfilaments; and small cells with round nuclei and a very scanty rim of cytoplasm. In two cases several concentrically folded cytoplasmic lamellae of glial processes were arranged either around themselves or around the perikaryon of other cells. This ultrasructural study indicates that GC is a neoplastic process of small undifferentiated elements, transitional forms of astroglia (to oligodendroglia) and anaplastic cells of astrocytic origin in all stages of development.
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  • 32
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    Virchows Archiv 411 (1987), S. 293-298 
    ISSN: 1432-2307
    Keywords: Ectocervix ; Serotonin cells ; Calcitonin cells ; Ultrastructure ; Transitional epithelium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A systematic study of endocrine cells in the ectocervix was carried out using histochemical, immunohistochemical and ultrastructural techniques. Serotonin and calcitonin immunoreactive cells were demonstrated in this site. Serotonin and calcitonin immunoreactivities were coexpressed in the same endocrine cell. These distinctive cells were encountered in two main morphological varieties of ectocervical epithelium. Normal-appearing stratified squamous epithelium contained only very rare serotonin and calcitonin cells. In contrast, endocrine cells were fairly abundant in a specific epithelium termed “transitional-like”. This type of epithelium was not only confined to the transformation zone but could also extend onto the portio as far as the vaginal cut margin. In some cases, transitional-like epithelium bore morphological resemblance to urothelium. In other cases, it could be regarded as basal cell hyperplasia or immature squamous metaplasia. Of interest, serotonin and calcitonin cells have been well-documented as normal inhabitants of some other non-squamous epithelia, such as urothelium or pseudostratified columnar epithelium. Therefore, it is suggested that certain ectocervical epithelia show some similarities to urothelium, in respect of their morphological appearance and endocrine profile. Further investigations using more objective and specific markers of urothelial cells are needed to assess the exact degree of homology connecting all these types of epithelium.
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  • 33
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    Virchows Archiv 412 (1987), S. 119-125 
    ISSN: 1432-2307
    Keywords: 16,16-dimethyl prostaglandin E2 ; Aspirin ; Tight junctions ; Stomach ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The canine gastric epithelium was exposed to solutions containing 20 mM aspirin and 20 mM aspirin + 30 µg/kg 16,16-dimethyl prostaglandin E2 (dmPGE2) for periods of three and forty minutes. No macroscopic hemorrhagic lesions were seen. Light microscopically, surface lesions were reduced from 10 percent (aspirin alone) to 2.5% (aspirin+dmPGE2). However, dmPGE2 does not appear to attenuate aspirin induced tight junction alterations. Discontinuities in the apical occluding complexes, hyperplastic tight junctions and stand number variability were documented in freeze frature replicas of aspirin as well as aspirin+ dmPGE2 treated dog stomachs. The results of these experiments would seem to suggest that 30 µg/kg dmPGE2 does not prevent aspirin induced damage to the tight junctions of the canine gastric epithelium or enhance their repair.
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  • 34
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    Virchows Archiv 411 (1987), S. 561-568 
    ISSN: 1432-2307
    Keywords: Psammous desmo-osteoblastoma ; Ultrastructure ; Osteonectin ; Bone tumours ; Fibro-osseous lesion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Fibro-osteo-cemental lesions of the jaw bones are a heterogeneous group of diseases which present problems in classification. Psammous desmo-osteoblastoma is one of four newly proposed entities (Makek 1983) and has until now been characterized by its light microscopic, clinical and radiological features. On electron microscopy this tumour exhibits fibroblastic (preosteoblastic), osteoblastic and osteocytic cells and a globular mineralization unlike the mineralization of the psammoma bodies. Immunohistological investigations with anti-osteonectin, a bone specific protein linking mineral to collagen, showed positive intracellular staining in all tumour cells and extracellular staining in the osteoid. The psammoma bodies were, however, not stained. These results confirm the view of the osteogenic histogenesis of psammous desmo-osteoblastoma, with an osteogenic differentiation of the tumour cells, bone formation and association of psammoma bodies which are not of bone origin. This combination of findings supports the view that psammous desmo-osteoblastoma represents a new and distinct entity occuring in desmal preformed cranio-facial bones which should be incorporated in a revised WHO-classification.
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  • 35
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    Virchows Archiv 410 (1987), S. 93-96 
    ISSN: 1432-2307
    Keywords: Heterogeneity ; Ultrastructure ; Colonic carcinoid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This report describes a colonic carcinoid tumor in which three, and possibly four, distinct cell types are distinguishable on the basis of their ultrastructure and granule morphology. These cell types closely resemble the normal endocrine cells of the large bowel, both in appearances and in relative frequency. The mixed composition of this tumor may have arisen either by parallel differentiation of distinct cell types, or by sequential maturation of one cell type.
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  • 36
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    Virchows Archiv 410 (1987), S. 317-326 
    ISSN: 1432-2307
    Keywords: “Primary” endothelial cilia ; Endothelial centrioles ; Human atherosclerosis ; Ciliary transitional fibers ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary “Primary” cilia were present in the endothelial cells of human aortic fatty dots and streaks but not in those of normal intima. They had the features of cilia of the “9+0” axonemal configuration observed in many other cells. A lateral foot process and transitional fibers “anchored” the ciliary basal body in the cytoplasm, but rootlets were not identified in material examined. Ladder-like configurations interconnected the two centrioles (=diplosome) of control endothelium. The “primary” cilia of endothelium differed from those of the rudimentary type observed in smooth muscle cells in similar lesions of man, but shared many features with cilia of those present in experimental atherosclerosis in rabbit. Cilia were rarely described in vascular endothelium. It is believed that, to date, they were not reported to occur in normal or pathological arteries in man. It is being stressed that whereas the significance of these unusual organelles remains uncertain, their widespread occurrence may indicate that their role is more important than was believed previously, and they should cease being a curiosity only.
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  • 37
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    Anatomy and embryology 176 (1987), S. 281-294 
    ISSN: 1432-0568
    Keywords: Myotendinous junction ; Human growth ; Skeletal muscle ; Tendon ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The myotendon junction of human paravertebral skeletal muscle was studied by light and electron microscopy. Transverse and longitudinal sections of myotendinous regions of normal multifidus muscles were examined at three chronological stages from birth to maturity. Variations in the appearance of surface extensions at the terminal ends of muscle fibers consisted of brush-like evaginations at birth and villous-like projections in the adult. Regardless of age, they were invariably covered by a prominent external lamina, and mutually interdigitated with connectivetissue elements in the adjacent tendon. Various stages of myofibrillar assembly and sarcomere alignment were evident in the muscle fiber terminus at birth. With advancing age, splitting of terminal sarcomeres at Z bands commonly gave rise to diverging myofilament bundles that attached to electron-dense patches under the sarcolemma. In these regions, leptomeric organelles were also encountered in neonatal and adolescent myotendons. At all stages, the ends of muscle fibers possessed cytological features consistent with active synthesis and secretion. Densely-packed sarcoplasmic organelles including multiple Golgi complexes, clusters of ribosomes, mitochondria, cytoplasmic vesicles, and elements of rough- and smooth-surfaced endoplasmic reticulum were prevalent. Peripheral and centrally-placed heterochromatic nuclei with prominent nucleoli were arranged singly or in groups at the ends of muscle fibers. Satellite cell profiles and unmyelinated axons in the subjacent tendon were also identified at these sites in the adult. Fibroblasts in growing tendon were plentiful, and at all stages, possessed morphological features indicative of high metabolic and secretory activities.
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  • 38
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    Anatomy and embryology 177 (1987), S. 131-138 
    ISSN: 1432-0568
    Keywords: Capillaries ; Tooth pulp ; Tight junctions ; Odontoblasts ; Ultrastructure ; Mineralisation ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The relative roles of capillaries and odontoblasts in the process of dentinogenesis and in pulp reactions to trauma and pathology are not clear. Contributing to the problem is the paucity of information on odontoblast —capillary relationships and tight junctions between odontoblasts. Using light microscopy the capillaries have now been examined in semithin transverse sections of perfusion fixed teeth at different positions in the long axis from the apical foramina to the pulp horns. Odontoblastic capillaries were prominent in the coronal and middle regions of canines and present at the same levels of incisors. In the pulp horns and just coronal to the pulp horns capillaries were all subodontoblastic but near the apex there were also a few odontoblastic capillary profiles. Transmission electron microscopy on ultrathin sections revealed that a high proportion of middle and coronal odontoblastic capillary profiles were fenestrated but subodontoblastic profiles coronal to the pulp horns were the most fenestrated. In a search for tight junctions in ultrathin sections some typical strands were observed between odontoblasts. The difficult of obtaining the latter evidence was explained by the cellular arrangement of the odontoblasts which differed markedly from an ideal parallel, apically coplanar arrangement. The results question the possibility that there is a direct exchange of materials between pulp capillaries and dentine in teeth of limited growth and provide a baseline for future experiments to test the permeability of the odontoblast layer.
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  • 39
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    Acta neuropathologica 73 (1987), S. 281-286 
    ISSN: 1432-0533
    Keywords: Teratoma ; Nervous tissue ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ultrastructure of the nervous tissue in a benign ovarian teratoma is described. This tissue was organized into areas having both “meningel” and “ependymal” surfaces, between which were found astrocytes, ependymal cells, neurones with synapses and microglia. These cells all had ultrastructural similarities to their normal counterparts in the nervous system. In addition, some signs of degenerative change — due possibly to the abnormal location of the nervous tissue — were observed. Oligodendrocytes and myelin were absent, possibly because of vascular insufficiency.
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  • 40
    ISSN: 1432-0533
    Keywords: Cerebellum ; Histogenesis ; Cisdichlorodiammineplatinum ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The aim of this electron microscopy study was to further investigate the effects of cis-dichlorodiammineplatinum (cis-DDP) on the cerebellum of the immature rat. Ten-day-old animals were treated with cis-DDP subcutaneously and killed after 1, 7, 15 or 21 days. On postinjection day 1, cis-DDP effects were evident mainly in the external granular layer, with nuclear damage in many dividing cells, while their cytoplasm appeared to be less affected. Some binucleate cells were also present. On the contrary, in postmitotic or more differentiated cells, only cytoplasmic alterations were found. At later stages (postinjection day 7), the frequency of damaged cells in the external granular layer decreased, but there was a cellular deficit in the internal granular layer. Many postmitotic neurons underwent coagulative necrosis. Finally (postinjection days 15 and 21), the cellular deficit was partly compensated for by “reactive” structures, e.g., glial cell fibers, which underwent hypertrophy after initial edema. Moreover, packing densities of Bergmann astrocytes and oligodendrocytes were higher.
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  • 41
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    Acta neuropathologica 73 (1987), S. 92-98 
    ISSN: 1432-0533
    Keywords: Spinal gliomas ; Vascular proliferation ; Ethylnitrosourea ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The histology and ultrastructure of ten spinal cord gliomas, mainly oligodendrogliomas, induced transplacentally in rat with ethylnitrosourea were studied. The characteristic feature of seven spinal tumours was distinct delineation of neoplastic tissue from the edematous surrounding zone by a ring of irregular, proliferating capillaries, among which immature capillary buds prevailed. The alterations were proliferation of endothelium with endothelial overlapping, elongation of interendothelial junctions and enhancement of pinocytotic vesicles on luminal and abluminal surfaces. The basal membranes, besides other changes, were often replaced by some floccular condensations. In the edematous zone the capillary walls were deprived of contact with glial processes. The lack of contact between astrocytic processes and vascular wall may contribute to the persistent immature state of peripheral capillaries.
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  • 42
    ISSN: 1432-0568
    Keywords: Serotonin ; Substantia nigra ; Mammals (rat, cat, Macaca fuscata) ; Immunohistochemistry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The distribution of serotonin-containing nerve fibers in the substantia nigra of the rat, cat and monkey was studied with a highly sensitive peroxidase-antiperoxidase immunohistochemical method. Serotonin fibers in the substantia nigra of all species consisted of fine varicose fibers and formed a fine network. In the zona compacta of all species, serotonin fibers were sparsely distributed. In the zone reticularis of the rat and cat, these fibers were densely distributed and their distributional pattern was almost uniform, while in the monkey such fibers were unevenly distributed and high and low dense areas were intermingled. In the pars lateralis of all species, serotonin fibers were diffusely distributed, and the distributional density was much higher in the cat and monkey than in the rat. Immunoelectron-microscopic studies further revealed that a majority of the labeled varicosities in the rat substantia nigra were in close apposition to peridendritic axon terminals and were also free in the neuropil; occasionally they exhibited symmetrical synapses of “en passant” type with non-immunoreactive dendrites or somata. Our results support a functional significance of serotonergic regulation of the substantia nigra in mammals.
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  • 43
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    Anatomy and embryology 175 (1987), S. 467-475 
    ISSN: 1432-0568
    Keywords: Mouse spermiogenesis ; Constitutive heterochromatin ; Nucleolus organizing regions ; Fluorochrome ; Staining ; EM silver staining ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In this study, the selective fluorochrome staining of constitutive heterochromatin and a specific ultrastructural silver-staining of nucleolar material (i.e., the nucleolus organizing regions) were undertaken to be used as indicators for the chromosomal arrangement during mouse spermiogenesis. Since in mice all somatic chromosomes are telocentric and the constitutive heterochromatin and nucleolar organizing regions are closely associated to the centromeres, this combination of techniques provided for the first time ultrastructural evidence 1) for the dispersion of the constitutive heterochromatic chromocentre and a centrifugal migration to the postacrosomal portion of the nuclear envelope where constitutive heterochromatin seems to mediate the assembling of microtubules in the so-called manchette. As elongation continues, the constitutive heterochromatin migrates back into central position and forms the “focous of earlier condensing chromatin”, which initiates further chromatin condensation. 2) The fate of the nucleolus during spermiogenesis could also be further clarified: The nucleolus is first associated with the chromocentre, but starts to disintegrate during elongation phase. However, argyrophilic remnants are still visible in the centre of the nucleus, pointing to an ongoing transcriptional activity. When they final disappear, they leave behind “nuclear vacuoles” in the dense chromatin mass of the mature sperm nucleus.
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  • 44
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    Anatomy and embryology 176 (1987), S. 35-40 
    ISSN: 1432-0568
    Keywords: Bovine ; Oocyte maturation ; Meiosis ; Nucleus ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Cumulus-oocyte complexes were obtained from cow ovaries by aspiration from small (1–6 mm in diameter) antral follicles after slaughter. Complexes with a compact multilayered cumulus investment were cultured and subsequently processed for electron microscopy after various periods of culture. By morphological criteria the oocytes could be divided into the following sequence of meiotic stages. The oocyte nucleus I stage was characterized by a spherical nucleus located peripherally in the ooplasm while undulation of the nuclear envelope and initial chromatin condensation was seen at the oocyte nucleus II stage. The oocyte nucleus breakdown stage was characterized by formation of long slender projections from the nuclear envelope in which the envelope doubled back on itself, appearance of dense areas and haphazardly oriented microtubules in the nucleus, marked condensation of the chromatin, and dissolution of the nuclear envelope into irregular vesicles and tubules. The condensed chromatin I stage was characterized by the location of condensed chromatin configuration and uniformly oriented microtubules in a dense area peripherally in the ooplasm while the final condensed chromatin II stage was characterized by a gradual invasion of condensed chromatin configurations into a dense area combined with the presence of the first polar body in the perivitelline space.
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  • 45
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    Anatomy and embryology 177 (1987), S. 91-96 
    ISSN: 1432-0568
    Keywords: Ultrastructure ; Human egg ; Human embryo ; Cleavage embryo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A two-cell human embryo recovered from the Fallopian tube 82 h following the LH peak in plasma and 37 h after a single episode of intercourse was examined by transmission electron microscopy. At the time of recovery the embryo was denuded of cumulus cells, and both the zona pellucida and the two adjoining blastomeres were intact. The finding of two polar bodies in the perivitelline space, two nucleated blastomeres and remnants of the fertilizing sperm tail within the cytoplasm of one of them, were considered as evidences that the embryo was normally fertilized. Among the most compicuous features found were the presence of very distinct desmosome-like structure between blastomeres, and the cytoplasmic cell organelles distribution in three areas referred as: a sub-cortical, a middle and a perinuclear bands. An outstanding feature was the extensive blebbing of the nuclear envelope. In general, the features seem to correspond to a normally developing two-cell embryo undergoing cleavage at a normal rate.
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  • 46
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    Anatomy and embryology 177 (1987), S. 147-152 
    ISSN: 1432-0568
    Keywords: Atrial myocardium ; Vagotomy ; Monkey ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ultrastructure of the atrial myocardium in the monkey (Macaca fascicularis) was studied after bilateral cervical vagotomy and survival times of 1, 3, 5, 7, 10, 21 and 28 days. During the first week after vagotomy, a few atrial cells showed a reduction in the sarcoplasm, crowding of the myofibrils, peripheral dispersion and reduced intercristal density of the mitochondria and increased sarcoplasmic reticulum and glycogen particles. In some profiles, there was increased electron density and granularity at the I bands and the intercalated discs. The number of such affected cells increased in the subsequent days such that by 21 to 28 days about 50% of the cells were estimated to be affected. During the latter stages further changes included, the degradation of the myofilaments and increased electron density, disorganisation and disintegration of the digital extensions at the intercalated discs. Throughout the experiments there was a leucocytic infiltration, more evident in the longer survival times.
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  • 47
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    Anatomy and embryology 175 (1987), S. 399-410 
    ISSN: 1432-0568
    Keywords: Implantation ; Marmoset ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ultrastructural morphology of the initial stages of implantation in the marmoset monkey (Callithrix jacchus) was studied in pregnant monkeys at known time intervals after ovulation. The earliest samples, obtained 13 days after ovulation, displayed both cytotrophoblast and syncytiotrophoblast. The cytotrophoblast was restricted to the blastocoel, whilst syncytiotrophoblast intruded to the endometrial basal lamina. At later stages, days 16 and 19 after ovulation, both cytotrophoblast and syncytiotrophoblast had extended laterally around the uterus, and the syncytiotrophoblast also extended deeper into the maternal tissnes. The mesoderm layer was first discernible at 19 days after ovulation. At 23 days after ovulation the syncytiotrophoblast surrounded the maternal blood vessels entirely. In this study syncytiotrophoblast was not observed to breach the maternal blood vessels, even at 31 days after ovulation. Early cytotrophoblast columns could be seen at 31 days after ovulation. The endothelial cells lining the maternal blood vessels displayed hypertrophy from the earliest stages (day 13) onwards, although a true decidual response was only observed in samples of 23 and 31 days after ovulation.
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  • 48
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    Anatomy and embryology 176 (1987), S. 41-44 
    ISSN: 1432-0568
    Keywords: Bovine ; Oocyte maturation ; Meiosis ; Gap junction ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Cumulus-oocyte complexes were obtained from cows by aspiration of small (1–6 mm in diameter) antral follicles after slaughter. Complexes with a compact multilayered cumulus investment were cultured and processed for transmission electron microscopy after different periods of culture including a 0 h control group. In 0 h control oocytes the cumulus cells had numerous projections which penetrated the zona pellucida and established gap junctions with the oolemma. A partial loss of these junctions was noticed as an early event of oocyte maturation occurring within the first 3 h of culture. A low frequency of gap junctions was maintained until 12–18 h of culture where the junctional contact was completely disrupted. This decrease in intercellular communication was parallelled by resumption of oocyte meiosis.
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  • 49
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    Anatomy and embryology 176 (1987), S. 231-237 
    ISSN: 1432-0568
    Keywords: Embryonic chick heart ; Interventricular septum ; Mesenchymal tissue ; Endocardial activation ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Light and electron microscopic studies of frontal and sagittal sections of embryonic chick hearts (Stages 25, 28–29), reveal mesenchymal tissue in the cephalic portion of the interventricular septum. The endocardium of this cephalic portion contains reoriented and invaginated cells with pseudopodia; in addition there are cells immediately subjacent to the endocardium. Similar cellular events take place during the formation of mesenchymal tissue in the atrioventricular and conotruncal regions. In these regions the mesenchymal tissue originates by means of an endocardial activation process. The structural characteristics of the formation of the cephalic portion of the interventricular septum suggest that local mesenchymal tissue is contributed by the endocardium. However, based upon the close anatomic relationship observed by us between the mesenchymal tissues of the atrioventricular canal, conotruncal region and the cephalic portion of the interventricular septum; we do not discard a contribution by migration of cells from atrioventricular and conotruncal regions to the interventricular septum.
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    Archives of dermatological research 279 (1987), S. 459-464 
    ISSN: 1432-069X
    Keywords: All-trans retinoic acid ; Epidermal cells ; Ultrastructure ; Differentiation ; Stratification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of all-trans retinoic acid on human epidermal cell cultures were studied using ultrastructural techniques. Differentiation and stratification were reduced in retinoic acid treated epidermal cells. Treated cells developed a rounded appearance and seemed to contain more granules and vacuoles than usual. Desmosomes were not found in treated cells.
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    Acta neuropathologica 75 (1987), S. 147-155 
    ISSN: 1432-0533
    Keywords: Esthesioneuroepithelioma ; Ultrastructure ; Immunohistochemistry ; Neurofilament protein (NFP) ; Keratin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A case of esthesioneuroepithelioma was investigated ultrastructurally and immunohistochemically, using antibodies against neurofilament protein (NFP), glial fibrillary acidic protein (GFAP), keratin, neuron-specific enolase (NSE), S-100 protein (S-100), and tyrosine hydroxylase (TH). The tumor initially manifested as an epidural mass in the anterior cranial fossa in a 64-year-old man, and about 31/2 years later, autopsy further revealed extensive metastases to the lymph nodes of the neck and thoracic cavity. In the cranial and nasal cavities, the tumor was composed of fairly uniform, ill-defined cells arranged in nests which were surrounded by a fibrovascular stroma. These histological features were reproduced in the metastatic tumor nodules with frequent occurrence of tubular arrangements of the tumor cells. Ultrastructurally, two different cell types were well recognized by their characteristic morphological features, which were reminiscent of sensory neurons and sustentacular cells of the olfactory epithelium. No dense-cored secretory granules were observed in the tumor cells. Immunohistochemically, the tumor showed a variable number of cells positive for NFP, keratin, NSE and S-100. NFP was present in a relatively small number of cells, which were found diffusely in the nests. Keratin was observed in the cells mainly located at the periphery. NSE-positive cells tended to form irregular clusters in the center. A few S-100-positive cells were found, without any particular arrangement. These findings indicated that the present tumor, which actually arose in the superior nasal cavity, consisted of cells differentiating in at least two distinct directions, neuronal and epithelial, and strongly suggested that the tumor was of true olfactory epithelium origin, or more precisely, derived from the bipotential, undifferentiated basal cells of this epithelium.
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    Acta neuropathologica 74 (1987), S. 307-312 
    ISSN: 1432-0533
    Keywords: Ganglioglioma ; Neuronal degeneration ; Ultrastructure ; Brain stem ; Brain tumor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A brain stem ganglioglioma in a 9-year-old female was examined ultrastructurally. The constituent neuronal (ganglion) cells displayed various ultrastructural features of neuronal degeneration including Hirano, Lafora and zebra bodies, inclusion-like aggregates of neurofilaments and large dilatations of rough endoplasmic reticulum. Although similar observations have been reported in peripheral neuronal tumors, this is the first reported occurrence in ganglioglioma, an uncommon tumor in the central nervous system. The coincidence of these alterations in the present tumor appeared to be of great interest, however, their exact etiology remained uncertain.
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  • 53
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    Acta neuropathologica 73 (1987), S. 400-402 
    ISSN: 1432-0533
    Keywords: Ultrastructure ; Ependyma ; Experimental hydrocephalus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary New ultrastructural alterations of the ependymal cells in the altered container model of experimental feline hydrocephalus are described. These include half desmosomes and a basal lamina on the apical surface of the ependymal cells, punctate adhesion-like structures between intraventricular mononuclear cell and the apical surface of the ependymal cells and unusual distortion of the ependymal cells. The significance of these previously unreported morphological alterations is unknown.
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  • 54
    ISSN: 1432-0533
    Keywords: Brain ; Global ischemia ; Ultrastructure ; Ionic changes ; Ca
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A time course of tissue ionic changes, and their relation to ultrastructural findings during reperfusion following a 15-min global ischemic brain insult was studied in a dog model. Parietal cortex was analyzed for Ca, Na, K, Mg and Fe in controls and after 10 min, 2, 4, and 8 h of reperfusion. After 8 h of reperfusion, the mean values (μmol/g tissue wet wt.) for Ca (control=1.43, 8 h=2.76) and Na (control 60.4, 8 h=107.4) doubled and K (control=90.4, 8 h=48.5) decreased to half that of the control. Ultrastructural studies and subcellular localization of calcium in parietal cortex of in situ-fixed brains after 8 h showed cortical neurons with clumping of nuclear chromatin, dilatation of endoplasmic reticulum and disruption of plasma membranes. Large amounts of electron-dense precipitates of calcium were present within dilated astrocytic processes, synaptic vesicles, cytoplasm of edematous dendrites and mitochondria. Cortical neurons from postischemic dogs without reperfusion showed only slight chromatin clumping and edema of astrocytic processes, but no calcium accumulation. The large ionic shifts noted between 4 and 8 h of reperfusion, indicate a progressive inability of the cells to maintain normal transmembrane gradients of these ions and may reflect a membrane destructive process, as demonstrated ultrastructurally at 8 h. Enhanced calcium entry into the neuron during reperfusion appears to be a part of the cytotoxic mechanism leading to neuronal necrosis.
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  • 55
    ISSN: 1432-0533
    Keywords: Intermediate filaments ; Glial fibrillary acidic protein (GFAP) ; Vimentin ; Ultrastructure ; Glioma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Glial filaments contain vimentin and glial fibrillary acidic protein (GFAP). The question of how glial filaments change morphologically according to the expression of vimentin and/or GFAP has remained unclear. In this study, immunohistochemical and ultrastructural examinations were performed on the subcutaneously transplanted tumors of two clones (F6B3 and G10A10) derived from a mouse glioma. F6B3 tumor expressed GFAP and vimentin in large quantities. G10A10 tumor expressed plenty of vimentin but only a little of GFAP. Ultrastructurally, F6B3 tumor contained abundant cytoprocesses in most of which numerous intermediate filaments (IFs) were arranged in a parallel array. On the other hand, only a small number of the processes were seen in G10A10 tumor, which showed a few IFs arranged either randomly or sparsely in the processes. Both tumors commonly had the IFs accompanied by visible sidearms, but there was a difference in that the smooth and firm IFs were confined to part of F6B3 tumor. Thus, the comparison made between the two models presented differences in the content, arrangement and morphology of IFs, as well as in the manner of GFAP expression, suggesting correlation between these differences.
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  • 56
    ISSN: 1432-0533
    Keywords: Neuronal ceroid-lipofuscinosis ; Membranous cytoplasmic body ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An autopsy case of adult neuronal ceroid-lipofuscinosis was examined. The clinical picture was charaterized by gait disturbance, bulbar palsy and dementia. Histopathologically, diffuse neuronal loss was found throughout the central nervous system. The remaining neurons, predominantly in the motor nuclei of the spinal cord and brain stem, were swollen with storage material. Observed under the electron microscope the storage material showed various ultrastructures, such as lipofuscin-like bodies, pleomorphic lipid bodies, curvilinear profiles and finger-print profiles, in different regions of the central nervous system. In the ballooned neurons of the spinal anterior horn, many membranous cytoplasmic bodies and curvilinear profiles were intermingled within the same cell and were continuous with each other. Biochemically,N-acetyl neuraminic acid content was significantly increased in the spinal anterior horn. These findings suggest the localized increase of ganglioside in that region.
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  • 57
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    Archives of dermatological research 279 (1987), S. 173-179 
    ISSN: 1432-069X
    Keywords: UV-A pigmentation ; Ultrastructure ; Morphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary UV-A-induced skin pigmentation was investigated morphologically in semithin and thin sections from 11 volunteers, using different irradiation modalities (single doses of 10,50 and 100 J/cm2). Visible skin pigmentation was observed in all but two probands, and erythema in two; pronounced pigmentation was present after repeated irradiation only. Contralateral non-irradiated, UV-B-irradiated and suntanned skin specimens were used as controls. There was an increase in the number of clear cells in the basal layer (x 1.6) and particularly of large clear cells (x 1.7) after repeated irradiation. Also, the number of melanosomes in melanocytic dendrites (x 2.8) increased after repeated irradiation. The number, size and shape of the melanosome complexes in both basal and suprabasal keratinocytes remained unchanged, even when a distinction was made between central and peripheral location. In contrast, suntanned skin showed an increase in melanosome complexes in basal (x 5.8) and suprabasal (x 3.7) keratinocytes. It is concluded that UV-A-induced skin pigmentation differs in some ways from UV-B or sun-induced melanogenesis, and that the clinical grade of tanning cannot accurately be determined by ultrastructural methods.
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    Development genes and evolution 196 (1987), S. 367-371 
    ISSN: 1432-041X
    Keywords: Vitellogenesis ; Bufo marinus oocyte ; Yolk-platelet membrane ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Oocytes of the toad Bufo marinus have been studied by means of thin section and particularly freeze-fracture electron microscopy to characterize the cytoplasmic membranes around the yolk organelle, and the storage of yolk material in precursors and platelets. This appears to be a previously unknown type of yolk-platelet formation. During yolk-organelle development from the primordial precursor to the bi-partite fully grown yolk platelet, numerous lipoid droplets are attached to the periphery of the platelet, indicating an intense uptake of lipids. As is typical for amphibians, the fully grown yolk platelet has a crystalline internum covered by a dense osmiophilic externum, and the whole organelle is enveloped by a plasma membrane that shows no direct connection or fusion with endocytotic vesicles. The yolk membrane exhibits few intramembraneous particles (IMPs) at the core areas and some more where it borders fields of lipoid droplets. Here the IMPs show a net-like arrangement in the furrows between adjacent droplets.
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  • 59
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    Experimental brain research 67 (1987), S. 41-51 
    ISSN: 1432-1106
    Keywords: Trauma ; Neuron ; Culture ; Calcium ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Cultured mouse spinal neurons were fixed at three different intervals after dendrite amputation: within the first 15 min, at 2 h and at 24 h. Dendrites were amputated at lesion distance of either 50 μm (31% probability of cell survival) or 100 μm (53% probability of cell survival) from the edge of their perikarya. When fixed within 15 min, operated neurons showed a two-phase gradient of ultrastructural damage which spread from the transection site towards the perikaryon. At 2 h after dendrite amputation all neurons operated close to their perikarya were categorized as either viable, moribund or dead, based on their appearance with phase contrast microscopy. These categories of response to physical trauma corresponded to distinctly different ultrastructural changes. Moribund neurons were filled with membrane-bound vesicles which were derived from swollen mitochondria and grossly dilated cisternae of the smooth endoplasmic reticulum. The cytoplasm of dead neurons contained large clear areas and many condensed, dark mitochondria. Both moribund and dead neurons lacked cytoskeletal elements. All of these ultrastructural changes are hypothesized to be the result of an increase in the intracellular concentrations of free calcium. Although evidence of residual mitochondrial swelling was present in some surviving neurons at 24 h, the ultrastructure of others was comparable to that of control cells. Some surviving neurons had terminal swellings at the ends of the severed neurites which were very similar to retraction balls of transected axons after CNS trauma.
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  • 60
    ISSN: 1432-0738
    Keywords: Silver toxicity ; Cultured macrophages ; Cell death ; Ultrastructure ; Lipid peroxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of silver on cultured mouse peritoneal macrophages were examined by estimation of cell survival and by light and electron microscopy. Additon of silver lactate to the culture medium at final concentrations of 40 and 80 μM resulted in coagulation necrosis and rapid cell death. At lower concentrations cell structure appeared normal. However, the rate of cell death at 20 μM silver lactate was increased as compared to controls. Silver, visualized by physical development/autometallography, was invariably located in lysosomes. The production of malondialdehyde in mouse liver of silver-treated mice as compared to controls was also examined. This lipid peroxidation product had increased to the same amount in animals treated with silver for either 3 days or with only one silver injection 4 h before examination. This study has demonstrated that silver affects viability and structure of cultured macrophages, possibly due to induction of lipid peroxidation, as demonstrated to occur in the liver of silver-exposed mice.
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    Archives of microbiology 148 (1987), S. 150-154 
    ISSN: 1432-072X
    Keywords: Bacteroides ; Vesicles ; Ultrastructure ; Cellulolytic bacteria ; Rumen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In 3-day-old cultures of Bacteroides succinogenes grown on filter paper, no cell division was observed. When grown on cellulosic substrate, bacteria exhibited vesicles clustered within cell wall pockets. In 2 day-old filter paper cultures, cells adhered tightly to the substrate. Twenty to 30% of them were dividing. There were cell wall pockets in about 25% of the bacteria, but no vesicles. Whether they adhered to the cellulosic substrate or not, and irrespective of the age of the bacteria, storage polysaccharides were found in the form of dense granules in the cytoplasm. It would appear that vesicles are not essential for cellulose degradation, but are rather a sign of ageing of the cells.
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  • 62
    ISSN: 1432-2307
    Keywords: Human heart ; Papillary muscle ; Myocardial hypertrophy ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An ultrastructural study using various electron microscopical techniques has been conducted on biopsy material from the hypertrophied papillary muscle of the human heart. About 75% of the myocardial cells were classified as hypertrophic with diameters ranging from 15 εm to 53 εm. The increased cell diameter appeared to be the result of an elevated amount of mitochondria and contractile material. The hypertrophied myocytes displayed a general ultrastructural organization in many ways similar to that of the normal sized myocytes. However, the former cells were characterized by focal deposits of excess laminar coat material and abnormal Z-band patterns as well as of multiple intercalated discs. The preferential sites for the production of new sarcomere elements appeared to be in the subsarcolemmal and intercalated disc regions. Adjacent myocardial cells were interconnected by collagen bundles, and, by an elaborate collagen-fibril-microthread-granule lattice. The surface folds were linked to each other by surface cables, which probably constituted a separate category of extracellular material of unknown function. Intramembranous particles were abundant in the sarcolemma proper but scarce in the membranes of the sarcoplasmic vesicles. Such particles were also observed in the lipofuscin granular membrane and in the membranes surrounding the lipid droplets. A framework of transverse cytoskeletal filaments interconnected the Z-bands of adjacent myofibrils and anchored the contractile material to the sarcolemma as well as to the nucleus. A large and lobulated nucleus containing well developed nucleoli together with an abundance of sarcoplasmic free and membrane-attached ribosomes, were interpreted as morphological signs of enhanced synthetic activity in the hypertrophied cell. Degenerative phenomena on the other hand were confined to lysosomal degeneration of worn-out cell constituents that were manifested by the numerous lysosomes and aggregates of lipofuscin granules. Abnormal Z-band patterns as seen in the present material were interpreted as an initial stage in the formation of new contractile elements.
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    Virchows Archiv 411 (1987), S. 267-273 
    ISSN: 1432-2307
    Keywords: Corticotropic adenoma ; Ultrastructure ; Pituitary oncocytoma ; Choroid Plexus carcinoma ; Mitochondrial morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The report documents a silent, oncocytic, ACTH-producing ectopic anterior pituitary tumour in a 6-year-old boy. The invasive intrahemispheric neoplasm had no connection with the pituitary gland, the sella turcica or the sphenoid sinuses. The apparent similarities existing between this tumour, some choroid plexus carcinomas and steroid-producing neoplasms are discussed.
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    Virchows Archiv 411 (1987), S. 283-291 
    ISSN: 1432-2307
    Keywords: Tumor invasion ; Ultrastructure ; Desmoplasia ; Squamous cell carcinoma ; Lung parenchyma ; Basal lamina
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Using ultrastructural methods we studied the interaction of tumour cells and lung parenchyma in deep areas (i.e., more than about 3 mm from the tumour surface) of 50 bronchogenic squamous cell carcinomas. The tumour periphery, studied previously, had shown organized associations of tumour cells and lung epithelial cells and a surprising lack of invasion of non-epithelial tissue compartments. The deeper areas, where the tumour cells and the lung parenchyma had been in contact for longer periods, consisted of irregular groups of tumour cells and desmoplastic stroma which was very similar to granulation tissue. The deeper areas also contained many intact lung epithelial cells, arranged in compressed and distorted alveolar structures. Where non-neoplastic epithelial cells and tumour cells had direct contact, they formed common junctional complexes and basal laminae. In part of the tumours, the cells were largely devoid of a basal lamina. However, in most instances a continuous basal lamina surrounded every tumour cell group studied, even when these formed irregular strands or seemed to be completely isolated.
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    Theoretical and applied genetics 74 (1987), S. 177-187 
    ISSN: 1432-2242
    Keywords: Barley ; Grain development ; Mutants ; Ultrastructure ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Eleven Na-azide induced barley shrunken endosperm mutants expressing xenia (sex) were characterized genetically and histologically. All mutants have reduced kernel size with kernel weights ranging from 11 to 57% of the wild type. With one exception, the mutant phenotypes are ascribable to single recessive mutant alleles, giving rise to a ratio of 3∶1 of normal and shrunken kernels on heterozygous plants. One mutant (B10), also monofactorially inherited, shows a gene dosage dependent pattern of expression in the endosperm. Among the 8 mutants tested for allelism, no allelic mutant genes were discovered. By means of translocation mapping, the mutant gene of B10 was localized to the short arm of chromosome 7, and that of B9 to the short arm of chromosome 1. Based on microscopy studies, the mutant kernel phenotypes fall into three classes, viz. mutants with both endosperm and embryo affected and with a non-viable embryo, mutants with both endosperm and embryo affected and with a viable embryo giving rise to plants with a clearly mutant phenotype, and finally mutants with only the endosperm affected and with a normal embryo giving rise to plants with normal phenotype. The mutant collection covers mutations in genes participating in all of the developmental phases of the endosperm, i.e. the passage from syncytial to the cellular endosperm, total lack of aleurone cell formation and disturbance in the pattern of aleurone cell formation. In the starchy endosperm, varying degrees of cell differentiation occur, ranging from slight deviations from wild type to complete loss of starchy endosperm traits. In the embryo, blocks in the major developmental phases are represented in the mutant collection, including arrest at the proembryo stage, continued cell divisions but no differentiation, and embryos deviating only slightly from the wild type.
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  • 66
    ISSN: 1432-0878
    Keywords: Subcommissural organ ; Innervation ; Neu rophysins ; Mesotocin ; Immunocytochemistry ; Ultrastructure ; Snake, Natrix maura
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The subcommissural organ (SCO) of the snake Natrix maura was studied by use of the immunoperoxidase procedure. Primary antisera against bovine neurophysins (Nps I + II, OXY-Np), oxytocin (OXY), mesotocin (MST), arginine-vasotocin (AVT), somatostatin (SOM), β-endorphin (END) and bovine Reissner's fiber were used. A conventional ultrastructural study, with special emphasis on the nerve fibers present in the SCO, was also performed. Nerve fibers containing immunoreactive OXY-Np and MST were seen to reach the SCO. The staining of adjacent sections with the anti-Reissner's fiber serum showed that the OXY-Np- and MST-immunoreactive fibers were distributed among the cell bodies and processes of the ependymal secretory cells. No fibers containing immunoreactive OXY, AVT, SOM or END were found in the SCO. The ultrastructural analysis revealed in the SCO the presence of nerve fibers filled with electron-dense granules, 170–210 nm in diameter. Although a direct apposition between these fibers and the SCO cells was frequently seen, no synaptic differentiations were identified. Structures identical to the Herring bodies (found in the neurohypophysis) were seen in the SCO.
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    Cell & tissue research 249 (1987), S. 421-425 
    ISSN: 1432-0878
    Keywords: Cholinergic synapses ; Ultrastructure ; Exocytosis ; Non-synaptic release ; Neuropeptides ; Carassius auratus ; Rana pipiens ; Wistar white rat ; Hamster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Nerve terminals forming typical synapses with adrenal chromaffin tissues have been examined in the goldfish, frog (Rana pipiens), hamster and rat. Presumptive secretory inclusions present in the terminals are of two distinct types. Electron-lucent synaptic vesicles 30–50 nm in diameter are densely clustered adjacent to membrane thickenings and presumably discharge their contents into the synaptic clefts. Secretory granules (i.e. large dense-cored vesicles) 60–100 nm in diameter are more abundant in other parts of the terminals. Sites of granule exocytosis have been observed in each of the animals investigated. They are usually encountered within apparently undifferentiated areas of plasmalemma and only rarely occur within synaptic thickenings. Granule exocytosis from within synaptic terminals and chromaffin gland cells is most readily observed in specimens exposed, prior to fixation, to saline solutions containing both tannic acid, and 4-aminopyridine and/or elevated levels of K+. These findings show that the pattern of secretory discharge, involving both synaptic and non-synaptic release, which is widespread in invertebrate central nervous systems, is also characteristic of vertebrate, peripheral cholinergic terminals.
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    Cell & tissue research 249 (1987), S. 437-442 
    ISSN: 1432-0878
    Keywords: Angiotensin II ; Glomerulus ; Salmo gairdneri ; Seawater-adaptation ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effect of angiotensin infusion on the glomerular ultrastructure of freshwater- and seawater-adapted rainbow trout, Salmo gairdneri, has been examined by scanning and transmission electron microscopy. Adaptation of trout to seawater resulted in epithelial podocyte flattening, primary process broadening and apparent loss of foot processes in almost all glomeruli, features which were uncommon in freshwater-adapted trout. Similar changes were induced by infusion of freshwater-adapted animals with angiotensin, suggesting that the renin-angiotensin system plays a role in the modification of glomerular epithelial ultrastructure. Adaptation of trout to seawater also reduced glomerular diameter, but infusion of freshwater-adapted animals with angiotensin did not mirror this effect. Infusion of angiotensin into seawater-adapted animals increased the overall thickness of glomerular basement membrane by increasing the lamina rara interna and lamina densa. This did not occur when freshwater-adapted fish were either infused with angiotensin or adapted to seawater. These findings suggest that other humoral systems are involved in the control of glomerular diameter and basement membrane thickness as part of an integrated response to increased environmental salinity.
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  • 69
    ISSN: 1432-0878
    Keywords: Leydig cells ; Ethane dimethanesulphonate ; Ultrastructure ; Degeneration ; Resistance ; Rodents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The morphological response of the testis of rats, guinea pigs, Syrian hamsters and mice to treatment with the cytotoxin ethane dimethanesulphonate was examined using light and electron microscopy. One to two days after a single administration of ethane dimethanesulphonate to adult rats, guinea pigs, and hamsters, the Leydig cells showed marked ultrastructural alterations suggestive of degeneration and cell death. The former alterations included karyopyknosis, cytoplasmic vesiculation and accumulation of lipid inclusions and large lipofuscin bodies. Fragments of necrotic Leydig cells were often engulfed by the interstitial tissue macrophages. The morphology of the seminiferous epithelium of these three species was unchanged from the morphology observed in vehicle-injected control animals. In contrast, multiple injections of ethane dimethanesulphonate given to mice produced no ultrastructural alterations to Leydig cells yet the seminiferous epithelium exhibited disruption of spermatogenesis. Although the Leydig cells of the mouse appear resistant to ethane dimethanesulphonate, this agent exerts a selective cytotoxic action upon Leydig cells of the rat, guinea pig and hamster thus identifying ethane dimethanesulphonate as a useful chemical for future endocrine and physiological studies of testicular function in three common laboratory species.
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  • 70
    ISSN: 1432-0878
    Keywords: Macula densa ; Intercellular spaces ; Ultrastructure ; Frusemide ; Tubulo-glomerular feedback ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In situ drip-fixation of superficial glomeruli and tubules in the rat kidney verified the results obtained from high pressure perfusion fixation studies indicating that distinct spaces normally exist between the cells of the macula densa. Following treatment with frusemide these intercellular spaces between the macula densa cells became closed in both drip-fixed and perfusion-fixed kidneys. These findings suggest that the variability of extracellular compartmentation found in the macula densa is unlikely to be an artifact but most likely represents changes in the in vivo status of the macula densa.
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  • 71
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    Cell & tissue research 247 (1987), S. 465-468 
    ISSN: 1432-0878
    Keywords: Adenylate cyclase ; Cytochemistry ; Gastrulation ; Ultrastructure ; Chick embryo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Adenylate cyclase activity was localized in various tissues of the early chick embryo using an ultrastructural histochemical technique. Reaction product was deposited on the lateral plasma membrane of all cells, but with a preferential localization at the apical terminal complex in the epiblast. There was no activity associated with the free surfaces of these or other cells in the embryo. Intracellular deposits were found in all cells associated with the endoplasmic reticulum, nuclear envelope and Golgi bodies. In the last organelle, the deposit was sometimes observed to be distributed through the stack in a non-uniform way, with the heaviest deposits occurring at the forming face. No clear difference could be detected between the cytochemical activity associated with cells in various regions of the embryo, or with embryos at different stages of early development.
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  • 72
    ISSN: 1432-0878
    Keywords: Gonadotropic cells ; LHRH analogue ; Pimo-zide ; Ultrastructure ; Goldfish ; Carassius auratus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effect of pimozide and an LHRH-analogue (LHRH-A) on gonadotropic cells of the goldfish pituitary gland were described qualitatively and quantitatively. A scale of four categories was devised to reflect various ultrastructural appearances of the cells. Experimental animals were divided into a control group, a group injected with LHRH-A alone, pimozide alone, and groups receiving these two substances in combination. Fish injected with the single substance were killed 12 h after injection while the groups receiving the combined treatments were killed at 4, 12 and 48 h. Serum levels of gonadotropin measured by radioimmunoassay were used to indicate whether an increase in hormone release had occurred. An immunocytochemical technique, the protein A-gold procedure, assured that the cells studied were gonadotropes. The control group showed variation in the profiles of gonadotropic cells. The single treatment groups showed some increase in secretory inclusions. At 4 h after injection the combined treatment caused a significant increase in hormone granules; at 12 and 48 h there was a gradual decrease in content of secretory products, and an increase in vacuolization. The results indicate that the combined pimozide and LHRH-A treatment stimulated gonadotropin production as well as release.
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  • 73
    ISSN: 1432-0878
    Keywords: Endolymphatic sac ; Calcium carbonate ; Otoconia ; Ultrastructure ; Frog (Hyla arborea japonica)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The endolymphatic sac of the tree frog and its crystals were observed by light- and electron microscopy. Scanning electron microscopy revealed that the crystals have a faceted body and two pointed ends. Light- and transmission electron microscopy revealed that the endolymphatic sac is composed of many small chambers. In their lumina, numerous “ghosts” of crystals that resulted from decalcification were observed. The ghosts were demarcated by a linear dense material or embedded in a flocculent substance. The epithelium of the endolymphatic sac is simple squamous or cuboidal and peculiar cytoplasmic granules are found in most cells. The granules are surrounded by a limiting membrane and have varying electron density. Some granules contain a core and/or tubular structures. Vacuoles containing large ghosts are also found in the epithelial cells. These ghosts were quite similar to those in the lumen and sometimes coexist with cell debris. The fine structure of the endolymphatic sac and its crystals is discussed.
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  • 74
    ISSN: 1432-0878
    Keywords: Epididymis ; Immunogold technique ; Ultrastructure ; Protein secretion ; Antagglutinin ; Boar
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Antagglutinin, a specific protein synthesized by the boar epididymis, was localized by an ultrastructural immunogold-labeling procedure in the principal cells of the three regions of the caput epididymidis, most notably at the sites of synthesis and secretion. The intensity of the reaction was variable in the three epididymal zones. Labeling was of low intensity in the proximal and middle caput, except in the granules of the latter. These granular “storage sites” did not correspond to typical secretory granules but appeared to be intracellular sites of degradation of this protein. In the distal caput, which was devoid of these granules, intense secretory activity for antagglutinin was detected. Few gold particles were localized in the RER profiles but labeling was detected in the Golgi zone, in numerous dense vesicles, in structures distributed between the Golgi zone and the apex of the cell, and in the epididymal lumen. This study has enabled us to visualize immunocytochemically antagglutinin along its intracellular secretory pathway, i.e. at the site of its synthesis, during its passage via the Golgi zone, and its intracellular transport to the lumen.
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  • 75
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    Cell & tissue research 247 (1987), S. 215-225 
    ISSN: 1432-0878
    Keywords: Kidney ; Endoplasmic reticulum ; Ultrastructure ; Membrane transport ; Metabolism ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The spatial organization of endoplasmic reticulum (ER) was examined in all segments of rat nephron. Tissues were fixed with glutaraldehyde, impregnated “en bloc” with osmium tetroxide, prepared for and examined by standard (80–100 kV) and high voltage (1 mEV) transmission electron microscopy. In all proximal tubule cells, ER forms a continuous and extensive network of canaliculi and abundant fenestrated saccules which surround mitochondria and cytoplasmic bodies; the cage-like structure of the fenestrated saccules was most evident around the spherical mitochondria of the S3 segment. In the cells of the distal straight and convoluted tubules, the network consists mostly of canaliculi with rare non-fenestrated saccules. The ER network of canaliculi is particularly rich in intercalated cells, in contrast with its rudimentary appearance in the adjacent principal cells of the collecting tubule. In fact, in these cells there are few isolated ER cisternae and they are rarely impregnated. The nuclear envelope is well impregnated in most cells throughout the various segments. Segmental variations in ER organization and its relative abundance are most likely related to the well, established functional heterogeneity of the nephron segments. Moreover, the extensive and unique organization among mitochondria, ER and the basolateral membrane suggests that these three organelles function as a unit which is related to active electrolyte transport. In addition, because of its transepithelial organization, ER may well constitute a transcellular pathway for molecules.
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  • 76
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    Cell & tissue research 247 (1987), S. 259-265 
    ISSN: 1432-0878
    Keywords: Epidermis ; Acidophilic cell ; Histochemistry ; Ultrastructure ; Salmo trutta ; Salvelinus alpinus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Sacciform cells containing an acidophilic, proteinaceous secretion, were identified in the epidermis of the brown trout and Arctic char. This cell type increased in number during the chronic stages of infestation by the ectoparasitic flagellate, Ichthyobodo sp., in immature brown trout, and decreased during sexual maturation in male brown trout and char. It is suggested that the salmonid sacciform cell produces a secretion which protects the fish against infestation or damage by skin parasites.
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  • 77
    ISSN: 1432-0878
    Keywords: Calcergy ; Calciphylaxis ; Cutaneous calcinosis ; Experimental calcification ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Skin calcification induced by topical calciphylaxis was provoked by a subcutaneous injection of iron chloride in rats previously sensitized by dihydrotachysterol. A cutaneous topical calcergy was induced by an injection of potassium permanganate. An electron-microscopical study of the long-term evolution of both these models of calcification was made. After the initial stages, mineralization of the connective tissue continued by a secondary nucleation process without matrix vesicles. The mineral composed of needle-like structures, apatite in nature, was mainly deposited between and around collagen fibrils, and showed various arrangements in calcified plaques. Intrafibrillar calcification was rarely observed and appeared only in the later stages. The extension of calcified deposits then stopped. Finally, there was a fragmentation of the mineralized area which was progressively surrounded by uncalcified collagen fibrils. A demineralization process, caused by cells such as macrophages and multinucleated giant cells, rather than a resorption of the calcified deposits, was noted. It is important to emphasize that, in both models of ectopic calcification, an evolution toward ectopic ossification was never observed, which is perhaps due to the absence of extensive resorption mechanisms.
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  • 78
    ISSN: 1432-0878
    Keywords: Sublingual gland ; Ultrastructure ; Golgi apparatus ; Rapid-freezing ; Freeze-substitution ; Gerbil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary We compare the ultrastructure of the gerbil sublingual gland as seen after cryofixation followed by substitution with osmium tetroxide, with the more familiar appearance of material processed by glutaraldehyde-osmium chemical fixation. After primary cryofixation of fresh salivary glands, the nuclei of the mucous cells are found to be spherical in shape and, rather than being displaced toward the cell base, occupy a nearly central position in the cytoplasm, even in the storage phase of the secretory cycle. The mucous secretory granules are seen as membrane-limited inclusions, only rarely partially fused to each other. In both mucous and serous cells the Golgi cisterns have numerous large fenestrae which are aligned to form cytoplasmic channels which extend across the stack.
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  • 79
    ISSN: 1432-0878
    Keywords: Retina ; Photoreceptor cells ; Freeze-fracturing ; Ultrastructure ; Immunocytochemistry ; Lampetra japonica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In common with other cyclostomata, the Japanese river lamprey (Lampetra japonica) has a retina consisting of distinct types of photoreceptor cells called long and short photoreceptor cells. After freeze-fracture, disc membranes of these photoreceptor cells were characterized in common by a homogeneous distribution of intramembrane particles on the protoplasmic fracture faces, in contrast to those of the myeloid bodies bearing scattering particles. Immunofluorescent examination was applied to the retina with monoclonal antibodies raised against bovine and chicken rhodopsins. Positive immunoreactivity was found to be limited to outer segments of the short cell, leaving the entire body of the long cell and all other components of the retina negative. The results suggest that the short cell is more closely related to a rod-type photoreceptor cell characterized by rhodopsin as its visual pigment.
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  • 80
    ISSN: 1432-0878
    Keywords: Tentacles ; Ultrastructure ; Adhesion ; Echinodermata ; Dendrochirodita (11 species)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The tentacles of eleven species of dendrochirote holothurians have been studied. The water vascular system, deep fibre system, ectoneural nerve ring and superficial fibre system are described and are similar to those of other holothurian tentacles. A conspicuous fuzzy coat covers the entire tentacular surface except for the tips of cilia. On the basis of its structure it is thought to be an attenuated glycocalyx. Its function is discussed in relation to anti-fouling and surface adhesion. The two surface coats underlying the fuzzy coat are termed the cuticle. Bacteria are found both within the surface coats and in the sub-cuticular space. Primary fixatives lacking osmium give poor preservation of the surface coats. The adhesive papillae of the apices of the tentacles contain elements of support cells and two other cells named Type-1 and Type-2 papillar cells. The secretions of Type-1 papillar cells are dense-cored vesicles and may contain a proteinaceous adhesive. The vesicles fuse with the cuticle and release their products which are apparently disseminated along the fuzzy coat filaments. The secretions of Type-2 papillar cells may have a neurosecretory function. The different models of food capture by dendrochirote tentacles are discussed as are duo-glandular adhesive systems in relation to dendrochirote tentacles.
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  • 81
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    Cell & tissue research 250 (1987), S. 513-519 
    ISSN: 1432-0878
    Keywords: Oocytes ; Structural patterns ; Pore canals ; Ultrastructure ; Salmonids ; Onchorhynchus tshawytscha, O. kisutch, O. gorbuscha, Salmo trutta, S. gairdneri, Salvelinus namaycush
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The zona radiata from unactivated and activated eggs from chinook salmon (Oncorhynchus tshawytscha), chum salmon (O. kisutch), pink salmon (O. gorbuscha), brown trout (Salmo trutta), rainbow trout (S. gairdneri) and lake trout (Salvelinus namaycush) were examined using scanning and transmission microscopy. The zona radiata in all species examined consisted of an outer adhesive coating, a thin densely staining zona radiata externa with pore canal plugs and a thick, fibrous zona radiata interna with a fibrous network on the inner surface. There was a two layer adhesive coating over the zona radiata externa in all species except pink salmon in which only one layer was observed. There were structural differences among species in the adhesive layer, zona radiata externa and plugs in the pore-canal openings.
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  • 82
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    Protoplasma 140 (1987), S. 13-21 
    ISSN: 1615-6102
    Keywords: Aconitum vulparia ; Endopolyploid antipodals ; Giant mitochondria ; Rough endoplasmic reticulum ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructure of antipodals ofAconitum vulparia Rchb. was studied at two stages of development: at the earlier stage the endosperm has several nuclei, at the later one the endosperm is multinucleate. Over the investigated period the antipodal size enlarges distinctly. The wall ingrowths increase in size and number. Finally, they occur throughout the antipodal walls except for a small area in the extreme chalazal part, sunk deep into the nucellar podium. There are no plasmodesmata in the antipodal cell walls. The cytoplasm is dense and rich in ribosomes; it shows weak vacuolation. The rough endoplasmic reticulum is well developed. At the later stage dilated cisternae of endoplasmic reticulum are formed. Mitochondria, plastids and active dictyosomes are abundant. At the later stage some giant mitochondria are present; their matrix contains a large clear area with fine fibrils and an aggregation of fibrillar material. At this stage of development plastids have two types of inclusions: electron-transparent vacuoles and aggregations of electron-dense granules. The giant endopolyploid nuclei are considerably larger than those at the mature embryo sac stage; they are lobed on all sides. During the studied periodA. vulparia antipodals seem to be at their most active state.
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  • 83
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    Protoplasma 140 (1987), S. 187-189 
    ISSN: 1615-6102
    Keywords: Chloroplast ; Inclusion ; Ribulose 1,5-bisphosphate carboxylase/oxygenase ; Spinach ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Rapid-freezing and substitution-fixation method revealed more detailedin situ ultrastructure of spinach intrathylakoidal inclusions, which cannot be recognized by anti-RuBPCase large subunit immunocytochemically. This supports the possibility that the intrathylakoidal crystalline inclusion is not RuPCase but some other molecule normally synthesized within the lumen.
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  • 84
    ISSN: 1615-6102
    Keywords: Chlorella ; Protoplasts ; Photosynthesis ; Osmotic properties ; Nonosmotic volume ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Protoplasts were prepared from cells ofChlorella saccharophila by treatment with a mixture of pectinase and cellulase. The yield of protoplasts is dependent upon the culture conditions prior to cell wall digestion. In thin section chemically-fixed protoplasts were without wall remnants at the surface of the plasma membrane. Of particular interest is the relationship between the Golgi apparatus and a nuclear envelope-endoplasmic reticulum continuum. Protoplasts have a photosynthetic capacity lying between 70 and 80% of that of normal cells, but show the same response towards CO2 concentration and DCMU inhibition. Protoplasts also respond to changes in the osmolarity of the surrounding medium in accordance with the Boylevan't Hoff equation as if they are an osmometer. The nonosmotic volume (NOV) was calculated.
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  • 85
    ISSN: 1615-6102
    Keywords: Alkaloid production ; Catharanthus roseus ; Plant cell culture ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Periwinkle (Catharanthus roseus) cells cultured in 1-B 5 medium display the ultrastructure of parenchyma cells. The parenchyma character remained unchanged when cells were exposed to any one of three different conditions effecting alkaloid accumulation. Transfer of cells to “alkaloid production medium” for 2 weeks (condition 1) accorded two special features,i.e., unusually big lipid droplets in the cytoplasm and, upon fixation, one or several electron-dense droplets of spongy precipitate in vacuoles. Among hormone-autotrophic cultures (condition 2) some cells showed a fine electron-dense vacuolar precipitate. Addition ofPhythium homogenate (fungal elicitor) to cells cultured in 1-B 5-medium for 10 days (condition 3), cells showed a frequent appearance of singular big lipid droplets in the cytoplasm, whereas vacuoles remained devoid of precipitate. The appearance of big lipid droplets and of vacuolar precipitate is interpreted as progressing cytodifferentiation, but is coincidental with alkaloid accumulation.
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  • 86
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    Protoplasma 137 (1987), S. 71-83 
    ISSN: 1615-6102
    Keywords: Alisma ; Embryogenesis ; Endopolyploidy ; Suspensor differentiation ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The development of the suspensor (consisting of a basal cell and a few chalazal cells) inAlisma plantagoaquatica andA. lanceolatum was investigated using cytochemical methods, light and electron microscopy. The basal cell becomes differentiated during the first three days of embryo development. As a result of endopolyploidization the volume of the nucleus rapidly increases, as does the quantity of chromatin it contains and the size of the nucleolus. As basal cell grows, its cytoplasm increases in volume and the number of organelles increase, and wall ingrowths begin to form on the walls at the micropylar pole of the cell. The full development and functioning of the suspensor occurs during the next three days. The enormous basal cell then attains its maximum degree of differentiation: its nucleus reaches a ploidy of 256n or 512n, the micropylar transfer wall is fully developed, as is the cytoplasm, rich in proteins, ribonucleic acids (RNA) and organelles, particularly dictyosomes and long cisternae of the rough endoplasmic reticulum. The chalazal suspensor cells joining the embryo proper to the basal cell also become differentiated. In the seven-day embryo the suspensor begins to degenerate which coincides with the cellularization of the endosperm at the micropylar pole of the embryo sac. The senescence of the suspensor involves the degradation of the nucleus, increasing cytoplasmic vacuolization, and a distinct decrease in protein and RNA content, first in the basal cell, then in the chalazal suspensor cells. Analysis of the development and ultrastructure of the basal suspensor cell suggests that it plays the role of an active metabolic transfer cell, translocating nutrients from the maternal tissues via the chalazal suspensor cells to the growing embryo proper.
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  • 87
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    Protoplasma 137 (1987), S. 145-155 
    ISSN: 1615-6102
    Keywords: Mistletoe fruit ; Phthirusa pyrifolia ; Ultrastructure ; Development ; Viscin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The viscin tissue ofPhthirusa pyrifolia consists at maturity of two different cell types. The first of these (viscin cells) are greatly elongated and have massive secondary walls, the microfibrils of which are arranged strictly transversely, and are soaked with mucilaginous noncellulosic polysaccharides. The second type of cells (vesicular cells) is much broader, with a very extensive vacuolar system and thin primary cell walls only. Viscin cells are capable of being stretched very greatly, the microfibrils of the secondary wall then becoming oriented more or less longitudinally. In nature, this corresponds to the time of attachement to the host surface, and is followed by drying and, possibly, shortening of the viscin cells. Developmental study of the tissue suggests that Golgi bodies are the major organelles participating in polysaccharide production. The actual mucilage seems to originate from three sources: an unorganized substance which accumulates between the plasmalemma and compound middle lamella; spherical vacuoles which seem to be embedded in the central vacuole, some of which are seen open to the outside of the cell; and from the dissolution at maturity of the compound middle lamella. It is suggested that the two types of cells may correspond to the two major functions of viscin, viz., host attachment (viscin cells) and nutrition of the disseminator (vesicular cells).
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  • 88
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    Protoplasma 137 (1987), S. 168-182 
    ISSN: 1615-6102
    Keywords: Nectary ; Secretion rates ; Strelitzia ; Sugar fluxes ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Flowers ofStrelitzia reginae grown at a constant 20°C have been shown to secrete nectar at a rate of up to 5.0 mg (d.w.) sugar h−1 (mean rate 1.2±0.1 mg h−1) for up to seven days. The nectar has a total concentration of about 25% during the early part of the secretory period but often falling to less than 10% towards the end of secretion. Each flower has three septal nectaries, the cuticle-lined ducts of which open into a nectar basin formed by the fused bases of two petals on the top of the receptacle. The layer of epithelial cells which secretes the sugars is thrown into highly convoluted folds and the distal parts of these cells have profuse wall inpushings. Both of these modifications have the effect of increasing the surface area of the plasmalemma apparently available for unloading the nectar. The glandular epithelium of the three, 26 mm long, nectaries of a single flower would be lined by more than 17×106 cells with a total plasmalemma surface area for unloading of at least 2,000 mm2. There is little evidence to suggest that secretion is a granulocrine process inStrelitzia. While there is abundant, stacked endoplasmic reticulum, and numerous vesicles containing fibrillar material, these do not appear to be directly concerned with sugar secretion. Data from specific flowers suggest that transmembrane fluxes in the range of 1.0×106 to 1.0×10−7 mol s−1 m−2 would be necessary to sustain the observed rates of secretion. While these are relatively high, when taken together with the structural information, they lead to the conclusion that secretion inStrelitzia is probably an eccrine process.
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  • 89
    ISSN: 1615-6102
    Keywords: Ultrastructure ; Erwinia amylovora ; Outer membrane ; Fixation procedure ; Cold storage ; Virulence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Modifications of the ultrastructure of the plant pathogenic bacteriumErwinia amylovora were analyzed according to growth conditions and fixation procedures. Six bacterial strains with various virulence characteristics were examined. Cultures were grown either in Yeast Peptone Glucose medium (YPG) or in a medium containing asparagine (ASP) supplemented with sorbitol (1% or 5% sorbitol). When grown in ASP + 1% sorbitol or in YPG, the strains, structurally similar to each other in ASP + 5% sorbitol, presented different frequencies of small evaginations which were observed arising from the cell surface mainly after an OsO4 fixation step. There was no correlation between the frequency of evaginations and the virulence of the strain. An overnight storage at 4 °C considerably enhanced the frequency of the evaginations. It was suggested that the OsO4 fixation step visualized differences in the bacterial outer membrane structure.
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  • 90
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    Protoplasma 137 (1987), S. 45-55 
    ISSN: 1615-6102
    Keywords: Carbohydrates ; Chilling effects ; Populus ; Sugars ; Ultrastructure ; Xylem ray cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructure of xylem ray cells inPopulus was studied in conjunction with their content of individual sugars and of starch. They differ considerably in structure and in carbohydrate content at the three chosen stages,i.e., of starch deposition (August), of starch maximum (November), and of starch dissolution (January). The transition from the summer to winter stage was also induced experimentally by storage of tissue at 0°C. Both in nature and after cold-storage, sucrose and its galactosides raffinose and stachyose were accumulated to a great extent, contributing up to 69.7 and 57.3% of total sugar content, respectively. They originated parallel to the breakdown of starch and to the appearance of abundant vesicular and dilated ER cisternae. Results indicating that they are the specific sites of sucrose accumulation, and/or its galactosides, are discussed. The occurrence of phytoferritin-like crystalloids in amyloplasts and of vacuolar flocculent material, which condenses into electron-dense bodies of suspectedly proteinaceous nature, is described.
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  • 91
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    Protoplasma 139 (1987), S. 100-104 
    ISSN: 1615-6102
    Keywords: Triticale ; Ultrastructure ; Fertilization ; Karyogamy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Karyogamy during fertilization inTriticale starts about 60 minutes after pollination. It was studied in the egg and the central cell by electron microscopy. The fusion of the sperm cell nuclei with the egg and central cell nuclei begins with nuclear envelope fusion presumably with participation of the endoplasmic reticulum cisternae. Initially, fusion is restricted to small bridges between the nuclei. It is accompanied by the appearance of intracisternal lipid droplets.
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  • 92
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    Protoplasma 140 (1987), S. 100-109 
    ISSN: 1615-6102
    Keywords: Actin ; Conifer ; Electron microscopy ; Picea glauca ; Somatic embryo ; Tissue culture ; Ultrastructure ; White spruce
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Somatic embryos in embryogenic callus cultures derived from Immature zygotic embryos ofPicea glauca (White spruce) were examined by light and electron microscopy. Somatic embryos consist of an embryonic region of small densely cytoplasmic cells subtended by a suspensor consisting of long highly vacuolated cells. Mitotic figures are frequent in the embryonic cells but are not observed in the suspensor. Cell divisions in the embryonic region apparently produce rows of cells which elongate to form the suspensor. The presence of abundant polysomes, coated membranes and dictyosomes in the cytoplasm of embryonic and upper suspensor cells suggests rapid growth of the embryo. In contrast the basipetal suspensor cells appear to be senescing. While only a few scattered microfilaments are present in the meristematic cells, the upper suspensor cells contain numerous bundles of longitudinally oriented microfilaments. These bundles correspond to actin cables observed in light microscope preparations stained with rhodamine labelled phalloidin and are oriented parallel to the direction of active streaming in these cells.
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  • 93
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    European journal of epidemiology 3 (1987), S. 187-195 
    ISSN: 1573-7284
    Keywords: Human intestinal spirochetes ; Swine intestinal treponemes ; T. hyodysenteriae ; T. innocens ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The ultrastructure of twenty human intestinal spirochetes was analyzed using the electron microscope. Negatively stained cells were generally found to be loosely and irregularly waved. The isolates had cell dimensions ranging from 0.12–0.35 μm in width and from 3.9–14.2 μm in length. Twin bundles of flagella were present in the space between the cytoplasmic membrane and the outer membrane. The majority of isolates had five flagella inserted sub-terminally at each cell end. Human intestinal spirochetes divide by binary fission. They are morphologically similar to swine intestinal treponemes, both pathogenic (Treponema hyodysenteriae) and non pathogenic (Treponema innocens), and different from Treponema pallidum, Treponema phagedenis and Borrelia burgdorferi. Following treatment with sodium deoxycolate, no bundles of cytoplasmic microtubules were observed in cells obtained from cultures of human and swine intestinal spirochetes or from cells of B. burgdorferi, while these structures were present in similarly treated cells of T. pallidum and T. phagedenis.
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  • 94
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    European archives of oto-rhino-laryngology and head & neck 244 (1987), S. 117-122 
    ISSN: 1434-4726
    Keywords: Endolymphatic sac ; Guinea pig ; Scanning electron microscope ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The subcellular structures of the epithelial cells of the guinea pig endolymphatic sac were studied. By using a newly developed scanning electron microscopy technique, the intracellular organelles could be studied three-dimensionally and the topographic relationships analyzed. The light epithelial cell has an extensive network of endoplasmic reticulum which is characteristically arranged in a basoapical direction. The connections between the inner surface of the plasmalemma and the endoplasmic reticulum were observed, as were connections between the Golgi complex and the endoplasmic reticulum. Our findings support the hypothesis that the endoplasmic reticulum might form transcellular channels through which the cell can transport water and ions from the lumen of the endolymphatic sac out into the subepithelial tissue. The dark epithelial cells seen in particular contained the smooth type of endoplasmic reticulum. Lysosomes were also observed in the dark cells, indicating that these cells probably have more of a secretory function.
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  • 95
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    Clinical rheumatology 6 (1987), S. 340-349 
    ISSN: 1434-9949
    Keywords: Rat Articular Chondrocytes ; Ultrastructure ; Morphometrical and Autoradiographical Evaluation ; Dexamethasone ; Chondroprotective Therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Quantitative ultrastructural morphometry and autoradiography of articular cartilage were used to assess in 3 months old rats the effects of in vivo administration of dexamethasone alone or in combination with a glycosaminglycan-peptide-complex (GAGPC). Dexamethasone treatment (3 mg/kg week for three weeks) induced a decrease of35S-sulphate incorporation in cartilage and ultrastructural changes of articular chondrocytes, mainly characterized by an increase in cell mortality rate, a decrease in length of endoplasmic reticulum, in the number of Golgi bodies and in mitochondrial pool and size. These autoradiographic and ultrastructural changes were reversed or prevented when GAGPC was administered concomitantly with dexamethasone. These results show that the modifications measured by quantitative ultrastructural morphometry of chondrocytes are consistent with changes in biosynthetic functions and that the GAGPC protects cartilage from the inhibitory effects of corticoids.
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  • 96
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    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 7 (1987), S. 91-95 
    ISSN: 0741-0581
    Keywords: Lead poison ; Ultrastructure ; X-ray microanalysis ; Intranuclear inclusion ; Concretion ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Intranuclear inclusions have been found in epithelial cells of renal proximal convoluted tubules (RPCT) in lead poisoned animals. It has been suggested previously that the inclusions contained lead. The present report gives evidence to the contrary. Samples of renal cortex were taken from adult rats fed laboratory chow containing 2% lead acetate for 1 month. Under the electron microscope (EM), intranuclear inclusions were observed in epithelial cells of RPCT. They were round or ovoid, and not delineated by a membrane. They consisted of two parts: Peripheral and central. Lysosomes increased in number, and many myelin figures appeared in the cytoplasm. In the lumen of the tubules, high electron-dense concretions were found. By x-ray microranalysis, neither the central part nor the peripheral part of the intranuclear inclusions produced a lead peak in the spectrum. Lysosomes and the cytoplasmic matrix also showed no lead peak. However, when the electron beam was focused on the concretion in the lumen of the RPCT, the Lα peak of lead (10.551 keV) and Kα peak of calcium (3.691 keV) were evident. From these findings it is suggested that intranuclear inclusions in the cells of RPCT are not lead deposits. Rather, it is the concretions found in the lumen of tubule that contain lead.
    Additional Material: 6 Ill.
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  • 97
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    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 7 (1987), S. 17-27 
    ISSN: 0741-0581
    Keywords: Exoplasmic cell surface ; Protoplasmic cell surface ; Ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Using rotary replication with platinum and carbon to embedment-free sections of polyethylene glycol (PEG)-embedded tissue from which PEG had been removed, the membrane specializations on the outer (exoplasmic) and inner (protoplasmic) cell surface as well as the organization of the cytoskeleton was demonstrated. The high quality and excellent preservation were comparable to that obtained by the rapid-freezing, deep-etched replica method. The present results indicate that the PEG method is essentially acceptable as a reliable morphological technique. Because either sectioned or replica images from the same tissue cells can be observed simultaneously, the PEG method with rotary replication should provide valuable information on cell ultrastructure.
    Additional Material: 12 Ill.
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  • 98
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    Hoboken, NJ [u.a.] : Wiley-Blackwell
    Journal of Orthopaedic Research 5 (1987), S. 231-241 
    ISSN: 0736-0266
    Keywords: Fibrocartilage ; Proteoglycans ; Collagen ; Postnatal age ; Ultrastructure ; Matrix ; Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: We report findings of a transmission electron microscopic study comparing the morphological appearance of cells and extracellular matrix of two fibrocartilaginous regions of canine flexor digitorum profoundus (FDP) tendon with that for typical tendinous regions. In addition, we determined the size distribution of collagen fibrils in six anatomical areas of the tendon from animals of three different ages. Average collagen fibril diameters for each of the six anatomical sites of 11-week-old FDP tendon were consistently different from that for older tissue. As growth proceeds, fibrils in tendinous regions almost double in size and take on a broad bimodal distribution. Collagen diameters in fibrocartilaginous areas do not increase, but rather decrease in size with age. Finally, the cells and associated pericellular matrix of fibrocartilaginous areas of adolescent and mature FDP tendon are ultrastructurally distinct from those of typical tendinous regions. On the contrary, the cellular morphology of 11-week-old tendon was invariant regardless of the anatomical region examined. In summary, fibrocartilage of canine FDP tendon, although not evident at 11 weeks of age, is well established by 6-12 months after birth and is the result of cellular and extracellular matrix specialization.
    Additional Material: 7 Ill.
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  • 99
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    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 7 (1987), S. 119-125 
    ISSN: 0741-0581
    Keywords: Ultrastructure ; Cytochemistry ; Megakaryoblastic leukemia ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Transmission electron microscopy, scanning electron microscopy, and ultrastructural cytochemistry were utilized to study megakaryoblastic cells from four patients suffering from megakaryoblastic leukemia. The results show that megakaryoblastic leukemic cells have a unique ultrastructural appearance, surface architecture, and cytochemical activity. The cells are positive for platelet peroxidase cytochemical reaction, which is localized in the perinuclear space and endoplastic reticulum, but not in the Golgi apparatus and cytoplasmic granules. They have a rather smooth surface and display blebs or tuberculi which are different from those in other types of leukemic cells as seen under the scanning electron microscope. The megakaryoblastic leukemic cells also show a special appearance under the transmission electron microscope, such as a cytoplasm which contains numerous small mitochondria, mostly concentrated in one pole of the cell. These ultrastructural and cytochemical characteristics of the megakaryoblastic leukemic cells revealed by the combined techniques are very useful in the diagnosis of megakaryoblastic leukemia.
    Additional Material: 6 Ill.
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  • 100
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    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 6 (1987), S. 143-153 
    ISSN: 0741-0581
    Keywords: Mauthner cell ; Mixed synapses ; Gap junctions ; Inhibitory synapses ; Ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Large myelinated club ending and small-vesicle bouton synapses on the distal part of the lateral dendrite of the goldfish Mauthner cell were investigated with thin section, freeze-fracture, and immunocytochemical electron microscopic methods. Large myelinated club endings form mixed synapses, having both gap junctions and chemical synaptic junctions. The correlation of the number of gap junction particles (connexons) and the data from electrophysiological studies of single large myelinated club ending synapses suggest that only a small fraction of gap junction channels are open at any given time during electrical synaptic transmission. The chemical synaptic junctions at the large myelinated club ending synapse have large, round synaptic vesicles, indicating that they are excitatory. This result is in agreement with electrophysiological data demonstrating the excitatory nature of this chemical synapse. Freeze-fracture of these excitatory chemical synaptic junctions reveals the presence of the intramembrane particle aggregates in the postsynaptic E face.Small-vesicle boutons form chemical synaptic junctions with small, flat or oval synaptic vesicles. These structural data, in combination with previous electrophysiological studies, suggest that the small-vesicle bouton synapses are inhibitory. In support of this theory, the cytoplasmic side of the postsynaptic membrane of some of these synapses show positive immunocytochemical reaction to monoclonal antibodies against the rat glycine receptor. Freeze-fracture data reveal intramembrane particle aggregates in the postsynaptic P face of some small-vesicle bouton synapses which could possibly represent glycine receptor aggregates.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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