大鼠视皮质胼胝体轴突的生后发育和形态──生物素结合的葡聚糖胺顺行示踪法研究

采用生物素结合的葡聚糖胺顺行示踪法研究了大鼠视皮质主要胼胝体投射区即１７／１８ａ交界区胼胝体轴突的生后发育和形态。在生后５天时，此交界区胼胝体轴突从白质向灰质Ⅰ层垂直生长，在灰质内仅有极少量的侧支抽芽。至生后１３天时，皮质Ⅰ层最先出现致密的由胼胝体轴突终支组成的终末丛。到生后１７天时，类似的终末丛也见于皮质Ⅱ／Ⅲ，Ⅴ和Ⅵ层，这种分布型式与成年大鼠者相似。以上结果表明，绝大部分胼胝体轴突首先生长到达Ⅰ层并先在Ⅰ层发出终支，然后再在其它皮质层发出侧支及终支，因而提示皮质Ⅰ层在胼胝体联系的生后发育中可能发挥重要作用。

POSTNATAL DEVELOPMENT AND MORPHOLOGY OF CALLOSAL AXONS IN THE RAT VISUAL CORTEX──AN ANTEROGRADE TRACING STUDY WITH BIOTINYLATED DEXTRAN AMINE

The growth and postnatal development of callosal axons in the rat visual cortex(with emphasis in theborder region between areas 17/18a)were investigated by means of an anterograde tracing method with biotinylated dextran amine(BDA).At the border region between areas 17/18a of postnatal day(PND)5 rat,BDA labeled callosal axons extended vertically or obliquly from the white matter to layerⅠof the grey matter with few collateral buds in the grey matter.On PAD 8,more callosal axons were found in the border and most of callosal axons reached layer.On PND 13,a distinct cluster consisting of many terminal arbors of callosal axons appeared for the first time in layerⅠ.From PND 17 to adult,dense clusters of callosal terminal arbors were also found in layeds Ⅱ/Ⅲ, Ⅴ and Ⅵ,in addition to the cluster in layerⅠ.The initial radial extention of callosal axons to layerⅠand the first presence in layerⅠof terminal clusters of callosal axons suggest that layer may play an important role in the postnatal development and maturation of callosal connections.