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  • 1
    ISSN: 1432-2307
    Keywords: Developing brain ; Extracellular space ; Cytotoxicity of ethylnitrosourea ; Matrix cell necrosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We observed the histological peculiarities of the repair process in a destructive lesion of the developing rat brain during neurogenesis. Degeneration was induced selectively in certain cells of the proliferating phase in the rat fetal neopallium on embryonic day 16 by transplacental administration of ethylnitrosourea. Successive elimination of necrotic cells and the restoration process were observed. The repair process was divided into the following steps. 1) Elimination of individually affected cells by phagocytes in the pre-existing extracellular space. 2) Successive restoration of the disintegrated area by cells wh ich differentiated from remaining matrix cells. No reactive gliosis, fibrosis, abnormal vascularization or infiltration of granulocytes and lymphocytes was observed at any time. The thinned neopallium on postnatal day 21 revealed only a small number and abnormal distribution of the cortical neurons. It may be assumed that the fetal brain owes its unique repair features to the presence of a vast extracellular space under normal conditions. In this pre-existing extracellular space, every kind of cell seems to exist separately without the intercellular adhesions characteristic of the adult brain. When degeneration occurs in certain cells the phagocytes would be able to eliminate the degenerate cells completely in this space without having to break intercellular adhesions. As a result, after the completion of cell elimination, the injured brain is restored to its original state with no cell reaction, giving the appearance of a small brain with normal-looking histological architecture, save only for the sparseness of cells.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2307
    Keywords: Developing spinal cord ; Cytotoxicity of ethylnitrosourea ; Matrix cell necrosis ; Neurogenesis ; Cytoarchitecture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We examined the histological findings and cytoarchitectonic alterations in the rat spinal cord following matrix cell degeneration caused at different developmental stages, from neural plate formation through neuroblast generation. Ethylnitrosourea (ENU) 20 mg/kg body weight was administered transplacentally to the fetuses on the 10th embryonic day (E10) to 14th. The observations were made until the 21st postnatal day. Normally, mitoses were present scatteredly in the matrix cell layer of the neural plate or neural tube on El0 or E11, and gradually restricted to the dorsal portion of the alar plate as development occurred. The localization and number of degenerative cells as well as the site and degree of neuronal decrease in the completed dysgenetic spinal cord seemed to correlate with the topography and frequency of the mitoses in the matrix cell layer at the time of ENU administration. Disorder in the pattern of cytoarchitecture of neurons was not observed. The degree of hypoplasia of the white matter was proportional to the intensity of decrease of the spinal neurons. Aberrant myelinated fibers were not seen. No reactive gliosis, fibrosis or abnormal vascularization was observed at any time.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2307
    Keywords: Basement membrane ; Capillary growth ; Seamless endothelial cell ; Regenerating capillary ; Experimental cerebral infarction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Ultrastructural analysis of capillary changes during the repair process of experimental cerebral infarction induced in rats was carried out with special reference to the endothelial basement membrane (BM) and seamless-type endothelial cells. Following degeneration of endothelial cells and pericytes, their BMs, without any interruption or fragmentation, were left in the lesion. Newly formed capillaries grew from vessels in the surrounding brain tissues into the reactive zone of infarcts. While the capillaries in cross-section possessed multilayered BMs, these membranes in tangential section comprised an outer BM with extremely wavy profile and an inner one showing a normal trilayered structure, uniformly enveloping the endothelial surface. It is therefore suggested that the sprouting of regenerating capillaries might invade the remaining cavities of BM, resulting from endothelial degeneration. In these new vessels, seamless-type endothelial cells lacking interendothelial contacts were observed frequently. These two different and previously unobserved findings appear to be at the heart of the regeneration mechanism of reactive capillary proliferation.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-2307
    Keywords: IGF-II ; Carotid body Extra-adrenal paraganglioma ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Insulin-like-growth factor (IGF)-II-like immunoreactivity was examined in two carotid bodies and six extra-adrenal paragangliomas with use of monoclonal antibody against rat IGF-II, which crossreacts with human IGF-II. Chief cells but not sustentacular cells of the carotid body were positive at about 10% in one case and less than 1% in another case. Among four carotid body tumours, a possible vagal body tumour and one glomus jugulare tumour, all but the glomus jugulare tumour exhibited positive tumour cells irrespective of histological variations. The frequency of positive cells ranged from 20 to 60%. IGF-II like immunoreactivity, therefore, might be widely distributed in human extra-adrenal paraganglionic tissues and tumours, although its biological role in these cells remains to be elucidated.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 171 (1985), S. 129-138 
    ISSN: 1432-0568
    Keywords: Cerebrovascular development ; Microvascular architecture ; Rat cerebellum ; Scanning electron microscope ; Vascular casting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary External and internal microvascular architectures of the developing rat cerebellar cortex, from embryonic day 18 to postnatal day 14 and in adults, were studied using a cerebrovascular casting method for scanning electron-microscopic observation. The external vascularization of the developing cerebellum showed the most significant alteration in vascular morphology at the stage of intensive proliferation of matrix cells in the external granular layer (EGL) from birth to postnatal day 4. It consisted of multiple luminal protrusion of the vessels, septum formation in the lumina, and small, ring-like anastomoses. Moreover, at the end of this stage, these structures of the vessels disappeared and the subarachnoid space was filled with newly-formed microvascular networks. Thereafter, architectural change of the developing pial vessels was mainly accomplished by elongation of each contorted vessel of the network. Concerning internal vascularization, a few vessels connected with the pial vessels were observed in the cerebellar plate forming a loose, simple network in the deeper neural parenchyma before the stage of foliation began. During the period of thickening of the EGL, however, there was no alteration in vascularity of the parenchyma other than the architectural changes proportionate to the newly-formed folia. It was during the synaptogenetic stage in the internal granular layer that the earliest intraneural vascular plexuses were formed. The vascular network in the molecular layer was formed after disappearance of the EGL. These findings suggest that vascular proliferation correlated with EGL-formation pertains to the pial vessels, and not the intraneural ones, which develop after neuronal cell migration in the developing cerebellum has taken place.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 239 (1985), S. 271-278 
    ISSN: 1432-0878
    Keywords: Brain macrophage ; Fetus ; Histogenesis ; Immunohistochemistry ; Monoclonal antibody ; Mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A study on the localization of fetal and neonatal brain macrophages of mice from embryonic day 10 (E10) to postnatal day 21 (P21) was carried out immunohistochemically using a monoclonal antibody against a macrophage differentiation antigen (Mac-1) and the labeled avidin-biotin technique. In the central nervous system, the macrophages recognized first were mainly located in the choroid plexuses of the fourth and lateral ventricles at E14. Their number increased at E17–P3 and gradually decreased thereafter. In the cerebral parenchyma, a few macrophages appeared at E14 in the matrix cell layer. They were also detected in the migrating zone at E15, E17 and in the cortical plate at E19. Mapping of positive cells at the stage of neuroblast formation (E15, E17, E19) disclosed the precise distribution of cerebral macrophages. The macrophages that appeared first in the choroid plexuses at E15 may be derived from the subarachnoid vessels, which extend into the stroma of the choroid plexuses when the matrix cell layer invaginates into the lateral ventricle to form the choroid plexuses. Almost all of the macrophages recognized in the cerebral parenchyma disappeared at P9 when the cytoarchitecture seemed to be completed. In the cerebellum, which develops later than the cerebrum, macrophages appeared after birth and were located mainly in the internal granular layer. The brain macrophages always appeared in the regions where cell proliferation and brain remodeling are most active at each stage. These findings suggest that fetal and neonatal brain macrophages may play an important role in scavenging degenerated cells and cell debris during histogenesis of the central nervous system.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1433-0350
    Keywords: Pontine glioma ; CT ; Histopathology ; Correlative study ; Coagulation necrosis ; Chemotherapy ; Irradiation therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Correlative study of computed tomography (CT) and pathologic findings was performed in eight cases of pontine glioma. All patients except one had chemotherapy and radiotherapy, with no surgical intervention. On initial CT scans, all patients had hypodense lesions in part or the whole of the pons, and there was evidence of mass effect. Four of eight cases showed contrast enhancement. After chemotherapy and radiotherapy, swelling of the pons and the width of the hypodense areas decreased. The hypodense areas sometimes became isodense in correlation with clinical amelioration. After several months of remission in responding cases, ring-enhanced lesions reappeared at the primary site, together with recurrent neurological signs. Pathological study postmortem was focused on the histological counterparts of the CT findings of central and perifocal hypodense areas and contrast enhancement. In six of seven treated cases, the central hypodense area surrounded by ring enhancement was shown to be coagulation necrosis. Higher cellularity and hypervascularity with glomeruluslike structures of small vessels were generally observed in enhanced areas. The areas diffusely infiltrated by tumor cells, but not enhanced in CT scans, had few abnormal vessels. Tumor cells were seen not only in hypodense areas around the enhanced portion but also in areas far beyond the enhanced portion. Exophytic expansion of tumor was observed in two cases on postmortem examination. One of these was detected by CT scans before death.
    Type of Medium: Electronic Resource
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