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  • Streptozotocin diabetes  (7)
  • Crystalloid aggregates  (1)
  • 1
    ISSN: 1432-0428
    Keywords: Streptozotocin diabetes ; hypothalamus ; pituitary ; testes ; morphology ; immunohistochemistry ; LH ; LHRH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The hypothalami, pituitaries and testes from streptozotocin-treated and control male Wistar rats were examined by light and electron microscopy 12 months after induction of diabetes. Light and electron microscopic immunohistochemical techniques were employed for the localization of luteinizing hormone-releasing hormone and luteinizing hormone in the hypothalami and the pituitaries. In the hypothalami of diabetic animals swollen neuronal processes containing anti-luteinizing hormone-releasing-hormone positive material were frequent. In the pituitaries of the same animals a large number of small luteinizing hormone-gonadotrophs was found. These cells contained numerous secretory granules and were deficient in endoplasmic reticulum. The average testicular weight of the diabetic rats was significantly reduced but with marked individual variations. Histologically, the testes with the highest weights appeared normal, those with the lowest weights atrophic with few degenerating Leydig cells. These hypothalamic-hypophyseal changes are probably responsible for the testicular lesions found in experimental diabetes mellitus and may have relevance to the problem of infertility in human diabetes.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 53 (1981), S. 99-106 
    ISSN: 1432-0533
    Keywords: Peripheral nerve ; Rat ; Streptozotocin diabetes ; Morphometry ; Morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary One year after beginning of the experiment seven streptozotocin-injected Wistar rats and seven controls were fixed by whole-body perfusion, the nervus radialis was dissected and processed for light and electron microscopy. After light-microscopic study standard photographs of nerve cross sections were measured by means of a semiautomatic image analyzer. The following measurements were obtained: (1) surface of fibers, axons, and myelin sheaths; (2) ratio of myelin to axon surface; and (3) percent of endoneural space. Group means and standard errors were calculated, and cumulated class distributions were made. Ultrathin sections from all animals considered morphometrically were studied qualitatively for ultrastructural changes. The quantitative study revealed in the diabetics reduction of average myelin surface, increase of endoneural space, and reduction of myelin/axon ratio. The main ultrastructural findings were lesions of Schwann and mesenchymal cells, followed by less frequent and less severe changes in axons and endothelium. These results suggest a primary Schwann cell lesion was responsible for the observed myelin reduction.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 54 (1981), S. 129-134 
    ISSN: 1432-0533
    Keywords: Peripheral nerve ; Rat ; Streptozotocin diabetes ; Morphometry ; Morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Eight streptozotocin-injected Wistar rats and eight controls were fixed by whole-body perfusion 4 months after beginning of the experiment, the nervus radialis was dissected and processed for light and electron microscopy. After light-microscopic study standard photographs of nerve cross sections were measured by means of a semiautomatic image analyzer. The following measurements were obtained: (1) surface of fibres, axons, and myelin sheaths, (2) ratio of myelin to axon surface, and (3) percent of endoneural space. Group means and standard deviations were calculated, and cumulated size class distributions were made. Representative nerve specimens from all animals were also studied by electron microscopy. The quantitative study revealed in the diabetics a severe reduction of the average myelin surface, a mild increase of axonal cross section and of endoneural space, a reduction of myelin/axon ratio and a mild reduction in cross section of the nerve. Ultrastructural lesions of minor degree were found in the cytoplasm of Schwann and mesenchymal cells, no lesion was observed in axons. These findings demonstrate the presence of neuropathy 4 months after induction of diabetes and support the pathogenetic role of the Schwann cell in our experimental model.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0533
    Keywords: Phrenic nerve ; Diaphragm muscle ; Rat ; Streptozotocin diabetes ; Morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary One year after beginning of the experiment six streptozotocin-injected Wistar rats and six controls were anesthetized and fixed by whole-body perfusion. The diaphragms were isolated and processed for light and electron microscopy. Both the intramuscular branches of the phrenic nerve and the muscle fibers were studied morphologically and morphometrically. Moreover, two diabetic and two control rats were killed by decapitation, the diaphragms were deep-frozen and studied histochemically for myofibrillar ATP-ase. A significant reduction of fiber cross section surface, due to reduction of both myelin and axon surfaces, was found in the phrenic nerves of diabetics. Lesions of Schwann and mesenchymal endoneural cells were the main ultrastructural changes. The diaphragm was much thinner in diabetics than in controls. In diabetics the number of lipid droplets found in red muscle fibers was increased and the white muscle fibers were hypotrophic. These findings were confirmed by the morphometric study. Ultrastructurally, various types of lipid droplets, streaming of Z line, organelle degeneration, invagination of nuclear membrane, and increase in number of satellite cells were found in red fibers of diabetic animals. Disorientation of the triads was the most frequent lesion in white fibers of diabetics. These results demonstrate that both neuropathy and myopathy are present in functionally related nerve and muscle from rats after 12 months of streptozotocin-induced diabetes. Both the dysmetabolic condition and the nervous lesions may have contributed to the muscular changes.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 66 (1987), S. 74-82 
    ISSN: 1432-1106
    Keywords: Preoptic area ; Suprachiasmatic nucleus ; Morphometry ; Rat ; Streptozotocin diabetes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Pituitary and gonadal disorders consistent with abnormal LHRH and LH secretion occur in streptozotocin-diabetic rats. A key role in the synthesis and regulation of LHRH and in the phasic LH release is played by the preoptic-suprachiasmatic region which is mainly formed by the medial preoptic area, the sexually dimorphic nucleus of the medial preoptic area, and the suprachiasmatic nucleus. Therefore we have studied this region by morphology and morphometry in normal and streptozotocindiabetic rats. In normal animals, the neurons of the above mentioned nuclei were morphologically and morphometrically dissimilar. Independent of their localization, reduced cytoplasmic and nuclear areas were observed in the neurons of diabetic animals. These lesions are consistent with hypotrophied neurons. Consequently, diabetes may impair both synthesis and regulation of LHRH and may therefore account for pituitary disorders, testicular atrophy, and lacking preovulatory LH peaks. The structural differences of the neurons of the three nuclei in normal animals underline their different physiological role. Yet, the similarity of the changes found in all three nuclei suggests a generalized hypofunction of the whole preoptic-suprachiasmatic region under diabetic condition.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 43 (1978), S. 69-75 
    ISSN: 1432-0533
    Keywords: Canine distemper ; Encephalomyelitis ; Malacia ; Pseudomyxovirus ; Crystalloid aggregates ; Tubuloreticular aggregates ; Picormavirus ; Arenavirus ; Vaccination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A 4-months-old, male, healthy dog developed CNS-symptoms 10 days after the second vaccination with live, attenuated distemper and canine hepatitis virus. The animal was euthanized after 2 weeks of illness. Light and electron microscopic examination of the CNS showed a partly necrotizing encephalomyelitis with numerous intranuclear and intracytoplasmic inclusion bodies, and the presence of probable pseudomyxovirus nucleocapsids and of crystalloid and tubuloreticular aggregates. Although there was conformity of inclusion bodies and probable viral structures as revealed by electron microscopy, the latter showed a much wider distribution. In addition, viral structures of a different type were found in polymorphonuclear leukocytes and vascular endothelial cells. Several morphological criteria led to the supposition that they are Picornaviruses, or possibly Arenaviruses. It is thought that their role in the disease process was at best an indirect one.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0533
    Keywords: Microangiopathy ; Hypothalamus ; Cortex ; Streptozotocin diabetes ; SHR-rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Basement membrane (BM) thickness of hypothalamic arcuate nucleus capillaries was measured in normotensive (WKY) and hypertensive (SHR) rats 4 and 8 months after streptozotocin or saline injection. Three groups were studied: controls (C), diabetics (D), and animals with impaired glucose tolerance (L). For comparison, BM thickness of cortical capillaries of an occipital, and a frontal area was measured in three different layers starting from the pial surface. Independently from strain, hypothalamic capillary BM was thicker in older than in younger animals. At both 4 and 8 months, BM thickness was lowest in C, highest in D, and intermediate (between C and D) in L. Hypertension combined with diabetes did not further increase BM thickness. In both C and D no difference was found between the two cortical areas. The BM thickness of C increased from the superficial to the deep layer. In C hypertension induced BM thickening in the superficial frontal and the deep occipital layer. In the intermediate and the deep layer of the frontal area BM was thicker in WKY-D than in WKY-C. In every layer BM was thicker in SHR-D than in corresponding controls. Hypertension combined with diabetes enhanced BM thickening in the intermediate and the deep layer of the frontal and in the intermediate layer of the occipital area. Degenerative changes occurred in hypothalamic and cortical pericytes. These changes were more frequent in hypertensive than in normotensive animals. In conclusion, a microangiopathy characterized by BM thickening and pericytic degeneration occurs in the brain of diabetic animals. Its intensity and enhancement by a concomitant hypertension vary from hypothalamus to cortex.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0533
    Keywords: Hypothalamus ; Cortex ; Neuronopathy ; Hypertension ; Streptozotocin diabetes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Diabetic encephalopathy is a relatively frequent late complication in human and experimental diabetes mellitus. Although it is generally assumed that microangiopathy plays a major role in its pathogenesis, many aspects of the latter are still poorly understood. To detect possible correlations between vascular and cellular changes, we examined in normotensive and spontaneously hypertensive streptozotocin diabetic rats the neurons of hypothalamic and cortical regions in which the capillary basement membrane thickness had been known from a previous study. Arcuate and ventromedial nucleus neurons of normotensive diabetic rats compared to those of corresponding controls showed a reduced cytoplasmic area after 4 but not after 8 months of experiment. No difference was found between hypertensive control and diabetic rats after either 4 or 8 months of experiment. After the 8th month cortical neurons of normotensive controls were smaller in an occipital than in a frontal region and within the same region in the following layer order: deep 〈 superficial 〈 intermediate. Neurons of hypertensive controls behaved comparably yet were generally smaller than those of normotensive controls in each corresponding region. Compared to those of control, cortical neurons of normotensive diabetic rats were smaller in superficial and deep layers of both regions and in the intermediate layer of the frontal region. Hypertension appeared to antagonize diabetes. Despite an arcuate nucleus microangiopathy found in rats from both strains after 4 and 8 months of diabetes, neuronal changes were seen only in normotensive animals after 4 months. In the intermediate cortical layer, where microangiopathy was most marked after 8 months of experiment, neurons were not or only slightly reduced in size. Further, hypertension, which aggravated microangiopathy in both cortical regions, antagonized diabetes-induced neuronal changes. In conclusion, it appears rather unlikely that microangiopathy plays a major pathogenic role in diabetic encephalopathy.
    Type of Medium: Electronic Resource
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