DEVELOPMENT OF THE HIPPOCAMPAL REGION IN THE RAT .2. MORPHOGENESIS DURING EMBRYONIC AND EARLY POSTNATAL LIFE
DEVELOPMENT OF THE HIPPOCAMPAL REGION IN THE RAT .2. MORPHOGENESIS DURING EMBRYONIC AND EARLY POSTNATAL LIFE
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DOI：
10.1002/cne.901900108
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发表时间：
1980-01-01
影响因子：
2.5
通讯作者：
BAYER, SA
中科院分区：
文献类型：
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作者：
BAYER, SA
观察了正常大鼠胚胎E10~E22天及出生后P1、P7、P21天整个海马区的形态发生，并与放射自显影结果(Bayer，‘’79c)进行了相关分析。这一区域被认为是由端脑中的两个相连的原基形成的，很容易在E16上识别。一个位于背内侧壁上，产生下丘脑束的一部分，即S角和齿状回。另一个位于后后壁，产生内嗅皮层以及部分副小结和小丘前。E17在推测的内嗅区出现皮质板；E19在皮质板中央出现细胞稀疏的纤维带。内嗅皮层层由外侧向内侧，由深向浅，第三层增厚最迟出现在E22。下丘的分层从E18开始，但直到E22才能区分副叶和前叶的浅层。推测S角E20上的锥体层较小，然后在E21-P1之间大大加长。在齿状回发育的早期，细胞从海马伞突起附近、脉络丛附近的神经上皮细胞向软膜下位置迁移。颗粒层的外侧肢在胎龄20时出现在齿状回的两端；胎儿期的外侧肢出现在围产期，发育迅速，到P7时形态上与外侧肢相似。用体积法对15~P21龄杏仁S角(包括部分下丘)齿状回、海马伞和穹隆的生长进行了定量分析。神经上皮细胞在出生后18天达到高峰，在出生后21天消失。室管膜下带在胎龄18岁时开始明显，胎龄20岁时达到峰值，到胎龄7岁时消失。在E16-E17和E22-P1之间，东方层和放射层、腔隙分子的生长速度很快。锥体层在E18-E19(可能是亚锥体)和E22-P1(可能是阿蒙‘S角锥体)之间快速生长。齿状门的生长速度在出生前迅速下降，而齿状颗粒层和分子层在出生后保持较高的生长速度。海马伞和穹隆有早期(E18-E19)和晚期(E21-E22)的生长突增。为了准确定位原始迁移细胞和有丝分裂细胞在杏仁S角和齿状回各层内的区域，比较了胚胎脑(E15-E22)中单次照射200RX射线后存活的细胞数量。神经上皮细胞从E15-E21开始增加其辐射抗性，并在E22达到对照水平；室管膜下区在整个发育过程中对辐射高度敏感。东方层和齿状门层的辐射抗性下降，并在E20达到最低点。锥体层、放射层、腔隙分子层和齿状颗粒层中70%以上的细胞在整个发育过程中都具有辐射抗性。
Morphogenesis of the entire hippocampal region was examined in normal rats from embryonic (E) day E10 to E22 and on postnatal (P) days P1, P7 and P21, and was correlated with autoradiographic datings (Bayer, ''79c). This region is postulated to form from 2 connected primordia in the telencephalon, easily recognizable on E16. One lies in the dorsomedial wall and generates a portion of the subiculum, Ammon''s horn and the dentate gyrus. The other lies in the dorsoposterior wall and generates the entorhinal cortex and part of the parasubiculum and presubiculum. A cortical plate appears in the presumptive entorhinal region on E17; a cell-sparse fibrous zone appears in the middle of the cortical plate on E19. Lamination in the entorhinal cortex proceeds from lateral to medial and from deep to superficial, with the thickening of layer III being the last to appear on E22. Lamination in the subiculum starts on E18, but the distinction between superficial laminae in the para- and presubiculum cannot be made until E22. The stratum pyramidale is small on E20 in presumptive Ammon''s horn, then greatly lengthens between E21-P1. In early dentate gyrus development, cells migrate from the neuroepithelium near the outgrowth of the fimbria and adjacent to the choroid plexus toward a subpial location. The ectal limb of the granular layer appears at the 2 extremes of the dentate gyrus on E20; the endal limb appears perinatally and develops rapidly to become morphologically similar to the ectal limb by P7. A volumetric analysis of growth in Ammon''s horn (including a portion of the subiculum) dentate gyrus, fimbria and fornix was made from E15 to P21. The neuroepithelium increases to a peak volume on E18 and disappears by P21. The subependymal zone becomes distinct on E18, reaches a peak volume on E20 and disappears by P7. Rapid rates of growth in the stratum oriens and strata radiatum, lacunosum-moleculare occur between E16-E17 and between E22-P1. The pyramidal layer grows rapidly between E18-E19 (presumptive subicular pyramids) and between E22-P1 (presumptive Ammon''s horn pyramids). Growth rates of the dentate hilus are rapid prenatally and decline postnatally, while dentate granular and molecular layers maintain high postnatal growth rates. The fimbria and fornix have early (E18-E19) and late (E21-E22) spurts of growth. To accurately locate regions of primitive migratory and mitotic cells within each lamina of Ammon''s horn and the dentate gyrus, the number of cells surviving a single exposure to 200 R X-rays in embryonic brains (E15-E22) were compared with controls. The neuroepithelium increases its radioresistance from E15-E21 and reaches control levels by E22; the subependymal zone is highly radiosensitive throughout development. Radioresistance in the stratum oriens and dentate hilus declines and reaches a low point on E20. Over 70% of the cells in the strata pyramidale, radiatum, lacunosum-moleculare and dentate granular layer are radioresistant throughout development.