Letourneau P C, Madsen A M, Palm S L, Furcht L T
Department of Cell Biology, University of Minnesota, Minneapolis 55455.
Dev Biol. 1988 Jan;125(1):135-44. doi: 10.1016/0012-1606(88)90066-8.
The first long tract to form in the brain of a vertebrate embryo is the ventral longitudinal pathway. In order to investigate what chemical cues may guide nerve growth cones along this pathway, affinity-purified antibodies to laminin and collagen type IV were used to stain sections of mouse embryos from Embryonic Days 8 through 17. A monoclonal anti-neurofilament antibody was used to show the development of the ventral longitudinal pathway in relationship to immunoreactivity for laminin and collagen type IV. At Day 8 fluorescent immunoreactivity for laminin is bright in the external limiting membrane of the neural tube, but the neuroepithelium does not show bright laminin or neurofilament immunoreactivity. At E9 the ventral longitudinal pathway is forming and punctate immunoreactivity for laminin is present on the surfaces of neuroepithelial cells in the marginal zone, through which axons of the ventral pathway extend. Punctate immunofluorescence for laminin remains concentrated in the marginal zone on Days E10 through E14, but on E16 punctate immunofluorescence was much reduced, although immunoreactivity for laminin remained bright in the maturing pial and arachnoid membranes and on blood vessels in the brain. Immunoreactivity for collagen type IV was strong in the external limiting membrane and on blood vessels, but never showed concentrated punctate immunofluorescence in the marginal zone. These results indicate that laminin may be available on cell surfaces and in extracellular spaces as an adhesive ligand for growth cones during the formation of the ventral longitudinal pathway.
脊椎动物胚胎大脑中形成的第一条长神经束是腹侧纵行通路。为了研究哪些化学信号可能引导神经生长锥沿着这条通路生长，使用了亲和纯化的抗层粘连蛋白和IV型胶原蛋白抗体对胚胎第8天至17天的小鼠胚胎切片进行染色。使用单克隆抗神经丝抗体来显示腹侧纵行通路的发育与层粘连蛋白和IV型胶原蛋白免疫反应性之间的关系。在第8天，神经管的外限制膜中层粘连蛋白的荧光免疫反应性很强，但神经上皮不显示明亮的层粘连蛋白或神经丝免疫反应性。在胚胎第9天，腹侧纵行通路正在形成，层粘连蛋白的点状免疫反应性出现在边缘区神经上皮细胞的表面，腹侧通路的轴突通过该区域延伸。在胚胎第10天至14天，层粘连蛋白的点状免疫荧光仍集中在边缘区，但在胚胎第16天，点状免疫荧光大大减少，尽管在成熟的软脑膜和蛛网膜以及脑内血管中层粘连蛋白的免疫反应性仍然很强。IV型胶原蛋白的免疫反应性在外部限制膜和血管中很强，但在边缘区从未显示出集中的点状免疫荧光。这些结果表明，在腹侧纵行通路形成过程中，层粘连蛋白可能作为生长锥的粘附配体存在于细胞表面和细胞外空间。
