Molecular and cellular characterization of the glial roof plate of the spinal cord and optic tectum: a possible role for a proteoglycan in the development of an axon barrier.
Molecular and cellular characterization of the glial roof plate of the spinal cord and optic tectum: a possible role for a proteoglycan in the development of an axon barrier.
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DOI：
10.1016/0012-1606(90)90203-u
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发表时间：
1990-04
影响因子：
2.7
通讯作者：
Diane M. Snow;Dennis A. Steindler;Jerry Silver
中科院分区：
文献类型：
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作者：
Diane M. Snow;Dennis A. Steindler;Jerry Silver
位于沿着轴突通路的战略位置的某些类型的神经胶质结构可以提供用于构建屏障的机械和/或化学元素，所述屏障可以在发育期间大体上指导轴突的伸长。顶板，一个假定的轴突屏障，位于沿着背中线发育的脊髓，并可能是重要的连合和背柱轴突的指导。我们检查了顶板，以确定该区域的发育形态，并确定当轴突在附近生长时，哪些分子与屏障功能相关。光和电子显微镜观察的顶板显示，这个胶质结构域经历了一个戏剧性的变化，从一个“楔”与细胞顶点之间的大细胞外空间在E12.5到一个薄，致密的隔膜与减少细胞外空间在E15.5。免疫细胞化学技术表明，高度唾液酸化的神经细胞粘附分子（N-CAM），碳水化合物识别的L2单克隆抗体，胆碱酯酶，阶段特异性胚胎抗原1，和配体，结合tetragonolobus purpureas凝集素的顶板表达。然而，这些分子也在脊髓的其他区域发现，这些区域允许或吸引轴突生长。当轴突靠近背中线生长但不穿过背中线时，顶板特有的分子是糖胺聚糖（GAG），硫酸角质素。硫酸角质素也存在于顶盖中线和其他非神经支配区域，如外表皮和发育中的软骨。我们的数据表明，硫酸角质素，单独或与顶板表达的其他分子相结合，可能是负责的，在一定程度上，通过顶板在胚胎脊髓轴突伸长的抑制。
Certain types of glial structures, located at strategic positions along axon pathways, may provide the mechanical and/or chemical elements for the construction of barriers which can grossly direct the elongation of axons during development. The roof plate, a putative axon barrier, is located along the dorsal midline of the developing spinal cord and may be important for the guidance of the commissural and dorsal column axons. We examined the roof plate to determine the developmental morphology of the region and to determine which molecules were correlated with the barrier function when axons were growing nearby. Light and electron microscopic observations of the roof plate revealed that this glial domain undergoes a dramatic change in shape from a “wedge” with large extracellular spaces between the cell apices at E12.5 to a thin, dense septum with reduced extracellular space at E15.5. Immunocytochemical techniques demonstrated that highly sialylated neural cell adhesion molecule (N-CAM), the carbohydrate recognized by L2 monoclonal antibody, cholinesterase, stage-specific embryonic antigen 1, and a ligand that binds tetragonolobus purpureas agglutinin are expressed by the roof plate. These molecules, however, were also found in other regions of the spinal cord which are permissive or attractive to axon growth. A molecule which is unique to the roof plate when axons grow close to, but do not cross, the dorsal midline is a glycosaminoglycan (GAG), keratan sulfate. Keratan sulfate is also present in the tectal midline and in other noninnervated regions such as the outer epidermis and developing cartilage. Our data suggest that keratan sulfate, alone or in combination with other molecules expressed by the roof plate, may be responsible, in part, for the inhibition of axon elongation through the roof plate in the embryonic spinal cord.