Altman J, Bayer S A
J Comp Neurol. 1985 Jan 1;231(1):1-26. doi: 10.1002/cne.902310103.
Short-survival and long-survival thymidine radiograms, and methacrylate-embedded tissue from normal and X-irradiated rat embryos were used to delineate the neuroepithelial source of the cerebellum and trace the earliest cell movements. The cerebellar anlage, crescent shaped, is demarcated by two ventricular landmarks, the anterior extension of the tela choroidea of the fourth ventricle and the embryonic cerebellar fissure. The cerebellar tela choroidea extends from the medullary fourth ventricle posteromedially to the lateral recess of the pontine fourth ventricle anterolaterally. The embryonic cerebellar fissure begins caudally as a single midline incision beneath the fused posterior cerebellar primordium, then splits to follow the unfused cerebellar halves, first separating each from the isthmus then from the pons. The cerebellar primordium is divided into three parts. The lateral cerebellar primordium caps the lateral recess of the fourth ventricle; it is contiguous with the pons medially and separated ventrally from the anlage of the cochlear nuclei by the tela choroidea. The subisthmal cerebellar primordium is situated beneath the isthmus, medially lining the isthmus canal. Laterally and posteriorly, it is continuous with the lateral and postisthmal primordia. The postisthmal cerebellar primordium caps the postisthmal recess of the fourth ventricle and extends to the medullary fourth ventricle. As we shall describe later, each of these primordia is a source of different components of the developing cerebellum. Most cells of the superficially located nuclear transitory zone are labeled with 3H-thymidine administered on day E14 but not thereafter. A high proportion of the cells of the deeper cortical transitory zone could still be labeled on day E15. This supports the assumption made earlier that the first is composed of differentiating deep neurons, the second of Purkinje cells. The cells of the nuclear transitory zone originate in the lateral cerebellar primordium near the junction with the tela choroidea prior to the formation of the germinal trigone and migrate in a superficial position medially. Beginning on day E16, the nuclear transitory zone splits into two components. One has transversely oriented cells that seem to be the source of a decussating fiber tract, presumably the hook bundle of Russell. The other is composed of longitudinally oriented cells that apparently contribute fibers to the ipsilateral superior cerebellar peduncle. The translocation of the cells of the nuclear transitory zone from the cerebellar surface to its depth, to form the deep nuclei, and the radial migration of the cells of the cortical transitory zone to the surfa
利用正常和经X射线照射的大鼠胚胎的短期存活和长期存活的胸苷放射自显影片以及甲基丙烯酸酯包埋组织，来描绘小脑的神经上皮来源并追踪最早的细胞运动。新月形的小脑原基由两个脑室标志划定界限，即第四脑室脉络丛的前伸部和胚胎小脑裂。小脑脉络丛从延髓第四脑室后内侧延伸至脑桥第四脑室外侧隐窝前外侧。胚胎小脑裂起始于尾侧，是融合的小脑后原基下方的单一中线切口，然后分开以追随未融合的小脑两半，首先将每一半与峡部分开，然后与脑桥分开。小脑原基分为三部分。外侧小脑原基覆盖第四脑室外侧隐窝；它在内侧与脑桥相邻，在腹侧通过脉络丛与蜗神经核原基分开。峡下小脑原基位于峡部下方，在内侧衬于峡部管。在外侧和后方，它与外侧和峡后原基连续。峡后小脑原基覆盖第四脑室峡后隐窝并延伸至延髓第四脑室。正如我们稍后将描述的，这些原基中的每一个都是发育中小脑不同成分的来源。位于表面的核过渡区的大多数细胞在E14天给予3H-胸苷后被标记，但此后未被标记。较深的皮质过渡区的细胞在E15天仍有很大比例可被标记。这支持了早先的假设，即第一个由分化的深部神经元组成，第二个由浦肯野细胞组成。核过渡区的细胞起源于靠近与脉络丛交界处的外侧小脑原基，在生发三角形成之前，并在内侧浅表层位置迁移。从E16天开始，核过渡区分为两个部分。一个有横向排列的细胞，似乎是交叉纤维束的来源，大概是拉塞尔钩束。另一个由纵向排列的细胞组成，显然为同侧小脑上脚贡献纤维。核过渡区的细胞从小脑表面向其深部移位以形成深部核，以及皮质过渡区的细胞向表面的径向迁移。
