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向前侵入端脑。我们的前期研究表明，鸡胚端脑细胞分泌硫酸软骨素蛋白聚糖（CSPGs），其糖链（硫酸软骨素，CS）阻止视网膜轴突侵入端脑区域，CS结构多样，富含D单位的CS分布于间脑端脑边界。在体外培养条件下，D单位CS在培养基质上的斑点可阻止视网膜轴突的侵入，而培养液中可溶性D单位CS对轴突的生长无影响，但可抑制D单位斑点的作用。结果表明，视束前缘向端脑方向移位，视网膜轴突异常进入端脑区，这是视束结构多样性决定轴突走行功能特异性的重要原因。视网膜轴突将D单位CS与其他类型的CS区分开来，这表明了感知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.