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  • 1980-1984  (3)
  • Fetus  (1)
  • Microcephaly  (1)
  • Synapse  (1)
  • 1
    ISSN: 1432-0533
    Keywords: Synapse ; Dentritic spine ; Purkinje cell ; Neuronal compensation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study was undertaken to elucidate morphological changes in the synaptic area of the Purkinje cell dendritic spines when granule cells were decreased in number. The mice were injected s. c. with 30 mg/kg b. w. of cytosine arabinoside on days 2, 3, and 4, and on days 7, 8 and 9, and were designated as group I and group II, respectively. The mice injected with saline on days 2, 3, and 4 served as control. The cerebella of the mice in each group were examined by electron microscopy on days 30, 60, and 90. Using photographs thus obtained, the synaptic length and area of Purkinje cell dendritic spines which participated in synapses with axons of granule cells were measured by computer. In the controls, these spines did not increase significantly either in synaptic length or in spine area in the duration from 30 to 90 days after birth. In the 90-day-old mice belonging to group I and group II, however, they increased by about 20% in the synaptic length and by about 35% in the spine area as compared to those in age-matched control. The elongation and enlargement show that the synaptic surface on the spine spreads to compensate for synapses lost by reduction in number of granule cells in experimental groups.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0533
    Keywords: Ultrastructure ; Fetus ; Nervous system ; GM1-gangliosidosis type 1
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The nervous system of a 22-week-old fetus with GM1-gangliosidosis type 1 was studied by electron microscopy. The tissues thus examined were the cerebral cortex at the parietal region, the cerebellum, the thoracic spinal cord, the Auerbach's myenteric plexus in the large intestine and the radial nerve fibers. In the cerebral cortex, membrane-bound vacuoles, which occasionally contained stacks of fine fibrils, were observed in the large young neurons in the deeper part of the cortical plate. The neurons in the other part of the cerebral cortex carried no storage materials. In the cerebellum, the membrane-bound vacuoles with stacks of fine fibrils were seen only in the Purkinje cells. The neurons in the spinal cord also contained several zebra-like bodies and the above membrane-bound vacuoles. As for the peripheral nervous system (PNS), neurons in the Auerbach's myenteric plexus carried membranous cytoplasmic bodies and zebra-like bodies. Some of the axons in the radial nerve fibers also contained a lot of pleomorphic electron-dense bodies and a few membranous cytoplasmic ones. These results show that the accumulation of storage materials is started in the large neurons which are produced in the early stage of neurogenesis in the central nervous system (CNS). Additionally, the observed membrane-bound vacuoles are considered to be structures which occur before the membranous cytoplasmic bodies and/or the zebra-like bodies. It is also elucidated that the PNS is affected earlier than the cerebral and cerebellar cortices and thoracic spinal cord.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0533
    Keywords: Cytosine arabinoside ; Mice ; Microcephaly ; Cerebral cortex ; Hippocampus ; Abnormal cytoarchitecture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Pregnant mice were treated with cytosine arabinoside on days 13.5 and 14.5 of pregnancy. Brains of the offspring were studied histologically. The matrix layer of the embryonic brains was extensively destroyed 12h after the injection of cytosine arabinoside, but regenerated partially on day 17 of gestation. In the cerebral cortex of 1-, 3-, and 5-day-old treated mice, abnormal clusters of young neurons were found on the surface of the developing cerebral cortex. Some clusters still had a supply of immature neurons from the remnants of the regenerated matrix layer. After 20 days, the clusters became gradually indistinct, although some vestigial groups of neurons were observed even after 120 days. In the hippocampus of young mice, the pyramidal cells decreased in number and were disarranged. Heterotopic pyramidal cell masses were found in the stratum radiatum and in the molecular layer of the dentate gyrus. Apical dendrites of pyramidal cells exhibited abnormal arborization. It was demonstrated by3H-thymidine autoradiography that young neurons in the abnormal clusters in the cerebral cortex were those produced in the matrix layer regenerated after the destructive change by cytosine arabinoside.
    Type of Medium: Electronic Resource
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