Developmental Biology 第三章神经系统的发育
Developmental Biology 第三章 神经系统的发育
Developmental Biology 神经管的形成 称为 neurulation。其方式分 primary neurulati0n的 神经管( neural tube是中枢神经系统的原基,其 secondary neurulation两种。 Primary neurulation: 由外胚层细胞增殖、内陷并最终离开外胚层表面而形 成中空的神经管。绝大多数脊椎动物前部神经管的形成采 用此种方式
Developmental Biology 一、神经管的形成 神经管(neural tube)是中枢神经系统的原基，其形成 称为neurulation。其方式分primary neurulation和 secondary neurulation两种。 1. Primary neurulation: 由外胚层细胞增殖、内陷并最终离开外胚层表面而形 成中空的神经管。绝大多数脊椎动物前部神经管的形成采 用此种方式
Developmental Biology 外胚层细胞的命运:背部中线区的细胞将形成脑和脊髓;中线区 外侧的细胞将生成皮肤;上述二者相交处的细胞为神经嵴细胞 neural crest),它们将迁移各处形成外周神经元、色素细胞、神经胶质细胞等。 Neural plate Neural fold /⑦ Neural cnst igure 7.2 Neurulation in amphibians and amniotes. (A) Diagrammatic representation of neural tube formation. The ectodermal cells are represented either as precursors of the neural crest(black)or as precursors of the epidermis(color). The ectoderm folds in at the most dorsal point, forming an outer epidermis and an inner neural tube connected by neural crest cells. B)Photomicrographs of neurulation in a 2-ay chick embryo. (C)Neural tube formation seen in transverse cross sections of the chick embryo at the region of the future midbrain (arrowheads in B). Each photo- raph in(C) corresponds to the one above it.(HE, head fold: HP, head process; IIN Epid Henscn's node: M, midbrain; NP, neural plate. )(Photomicrographs courtesy of R. Nagele
Developmental Biology 外胚层细胞的命运：背部中线区的细胞将形成脑和脊髓；中线区 外侧的细胞将生成皮肤；上述二者相交处的细胞为神经嵴细胞(neural crest)，它们将迁移各处形成外周神经元、色素细胞、神经胶质细胞等
Developmental Biology 神经管形成的起始:来自背部中胚层的信号诱导预 置神经板边缘的细胞的背测收缩,而预置的表皮细胞向 中线移动,使表皮与神经板交接处凸起形成神经褶。 mh MtMMliDy apical constriction cell movement Fig 8.29 Change in cell shape and cell crawling may drive ectoderm. This may be partly responsible for causing the neural neural folding. Cells at the edge of the neural plate change their folds to develop shape and appear to crawl along the undersurface of the adjacent
Developmental Biology 神经管形成的起始：来自背部中胚层的信号诱导预 置神经板边缘的细胞的背测收缩，而预置的表皮细胞向 中线移动，使表皮与神经板交接处凸起形成神经褶
Developmental Biology Primary neurulation的过程 (A)Formation of neural folds (B)Elevation of neural folds Presumptive 沙 Notochord DLHP DLHP Presumptive neural plate r Furrowing Transition zone MHP Wedging Neural plate Epidermis Anchoring Notochord Figure 7.4 anchored to the notochord the neural Schematic representation of the epithe- folds are elevated. These movements lial bending during chick neurulation. appear to be continued as the medially (A)Formation of neural folds occurs moving epidermis drags the neural when presumptive epidermal cells plate with it, resulting in the apposition move medially toward the center of the of the neural folds. (C)In the three embryo. This presumptive epidermis hinge regions(the medial hinge point, pushes the neural plate under it as it MHP and the two dorsolateral hing moves.(B)As the midline cells of the neural plate( the floor plate cells)are positions, the DLHP), the neural plate lls change their length and constrict at their apice
Developmental Biology Primary neurulation的过程