HIPPOCAMPAL DEVELOPMENT IN RAT - CYTOGENESIS AND MORPHOGENESIS EXAMINED WITH AUTORADIOGRAPHY AND LOW-LEVEL X-IRRADIATION
HIPPOCAMPAL DEVELOPMENT IN RAT - CYTOGENESIS AND MORPHOGENESIS EXAMINED WITH AUTORADIOGRAPHY AND LOW-LEVEL X-IRRADIATION
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DOI：
10.1002/cne.901580105
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发表时间：
1974-01-01
影响因子：
2.5
通讯作者：
ALTMAN, J
中科院分区：
文献类型：
--
作者：
BAYER, SA;ALTMAN, J
采用3h胸腺嘧啶放射自显影技术、低水平X射线照射引起的细胞固缩和定量组织学技术观察大鼠海马的细胞发生和形态发生。采用渐进式延迟累积标记法进行放射自显影。各组大鼠在从出生到第19天的非重叠期间连续每天注射四次3h胸腺嘧啶。60日龄处死，测定标记细胞百分比。阿蒙角的锥体细胞和齿状回的多形细胞在出生后没有被标记，证实了它们的产前起源的早期结论。在齿状回，85%的颗粒细胞是在出生后形成的，其中45%是在第一周形成的。齿状分子层和氨态层的大部分小细胞是在第二周形成的。为了确定发育过程中海马的增殖区室，并描述细胞分化和形态发育的时间过程，在一次200r X射线照射后6小时杀死年龄从妊娠第17天到出生后103天的大鼠，并对收缩细胞进行计数。阿蒙角细胞固缩在产前达到最高水平，在产后早期迅速下降。齿状回细胞固缩在出生后第二周达到最高水平，并逐渐下降，成人中仍存在一些放射敏感细胞。未成熟的颗粒细胞在出生后第二周也处于最高水平，而成熟的颗粒细胞逐渐积累，在大约两个月大时达到渐近水平。锥体细胞的排列形成阿蒙角的特征曲率发生在锥体细胞发生后不久。相反，从出生之日起，在颗粒细胞发生完成之前，齿状回的尖锐褶皱是明显的。本文还讨论了齿状回形态发育的可能机制以及颗粒细胞前体可能的迁移途径。
The cytogenesis and morphogenesis of the rat hippocampus was examined with the techniques of3H‐thymidine autoradiography, cell pyknosis produced by low‐level X‐irradiation, and quantitative histology.The procedure of progressively delayed cumulative labelling was used for autoradiography. Groups of rats were injected with four successive daily doses of3H‐thymidine during non‐overlapping periods ranging from birth to day 19. They were killed at 60 days of age, and the percentage of labelled cells was determined. The pyramidal cells of Ammon's horn and the polymorph cells of the dentate gyrus are not labelled postnatally, confirming earlier conclusions of their prenatal origin. In the dentate gyrus, 85% of the granule cells are formed postnatally, with 45% forming during the first week. The majority of the small cells of the dentate molecular layer and of the Ammonic strata oriens, radiatum, and lacunosum‐moleculare are formed during the second week.As an aid to locating the proliferative compartments of the hippocampus during development and to characterize the time course of both cell differentiation and morphological development, rats ranging in age from gestation day 17 to postnatal day 103 were killed six hours after one exposure to 200r X‐rays, and the pyknotic cells were counted. Cell pyknosis in Ammon's horn reaches a maximal level prenatally and declines rapidly during the early postnatal period. Cell pyknosis in the dentate gyrus reaches its highest level during the second postnatal week and declines gradually with some radiosensitive cells still present in the adult. Immature granule cells are also at their highest level during the second postnatal week, while mature granule cells gradually accumulate to attain asymptotic levels at around two months of age. The alignment of the pyramidal cells to form the characteristic curvature of Ammon's horn occurs shortly after pyramidal cell cytogenesis is completed. Conversely, the sharp fold in the dentate gyrus is apparent from the day of birth onward, before the completion of granule cell cytogenesis. Possible mechanisms for the morphological development of the dentate gyrus along with a consideration of the possible migratory route of granule cell precursors is also discussed.