Investigation for molecular mechanisms by which the retinal ganglion cells perceive carbohydrate chains of chondroitin sulfate proteaglycans (chondroitin sulfate) as axonal guidance cues

视网膜神经节细胞的轴突不会向前侵入端脑。我们以前的研究表明，鸡胚胎中的端脑细胞分泌硫酸软骨素蛋白多糖(CSPGs)，其碳水链(软骨素硫酸盐，CS)可以防止视网膜轴突侵入端脑区域。CSs结构多样，富含D单元的CS分布在间脑边界。在体外，D单位CS在培养底物上的斑点可防止视网膜轴突侵入，而培养液中的可溶性D单位CS对轴突生长无影响，但抑制D单位斑点的作用。为了了解D单位CS在体内视网膜轨迹形成中的作用，将D单位CS的溶液注入胚胎侧脑室，视束前缘向端脑移动，视网膜轴突异常进入端脑区域。结果表明，CS的结构多样性在轴突连接中发挥了其功能特异性。视网膜轴突将D单位CS与其他类型的CS区分开来，提示了感知CS多样性的机制。

Axons of retinal ganglion cells do not invade the telencephalon anteriorly. Our previous researches have shown that the telencephalic cells secrete chondroitin sulfate proteoglycans (CSPGs), and that their carbohydrate chains (chondroitin sulfates, CSs) prevent the retinal axons from invading the telencephalic territory in chick embryos.CSs exhibit their structural diversity ; the D unit rich CSs was distributed in the diencephalotelencephalic boundary. In vitro, spot of the D unit CS on the cultural substrate prevented the retina axons from invading ; however, soluble D unit CS in the culture medium has no effect on the axon outgrowth but inhibit the effect of D unit spot.To know roles of D unit CS in formation of the retinal trajectory in vivo, solution of the D unit CS was injected into lateral ventricle of the embryos ; anterior border of the optic tract shifted toward the telencephalon and the retinal axons entered the telencephalic territory aberrantly.The results indicate that structural diversity of the CSs serves their functional specificity in axon wiring. The retinal axons distinguish the D unit CS from other types of CSs, suggesting mechanisms perceiving the CSs' diversity.