胎儿脑动脉分叉部构筑发育的研究

Study of the development characteristics of intracranial artery bifurcations in human embryos.

目的 探讨人类胚胎脑动脉分叉部弹力纤维和中层平滑肌细胞(smooth muscle cell,SMC)的构筑发育过程及特点。方法 收集胎龄12-28周人类胚胎共17例,每1个周龄取1例,男女不限.对胎脑Willis环周围的动脉分叉部行不同方向组织切片,观察弹力纤维和中层SMC的构筑发育过程。结果 胎脑Willis环周各动脉弹力纤维在1.5-12.6层之间,弹力纤维在同一切片有紊乱和逐渐减少现象,内弹力层第19周发育完整;中层SMC在1.1-9.0层之间,70.6％的胎脑动脉个别分叉部发现中层SMC缺陷,所取标本的30.3％发现中层SMC缺陷。结论 胎脑动脉内弹力纤维和中层SMC随胎龄增长而增多,内弹力层于第13-19周出现并发育成熟,脑动脉分叉部存在先天性SMC缺陷、弹力纤维紊乱和逐渐减少现象,有助于对脑动脉瘤病因假说的理解和验证。

Objective To explore the deveolpmental characteristics of elastic fibers and medial smooth muscle cells (SMC) at the bifurcations in human fetal intracranial arteries. Methods From 17 normal fetuses aged ranging from 12 ~ 28 weeks, segments of the Willis' arteries (including bifurcation) were harvested and sectioned in 1 of 3 orthogonal planes. The 3 dimensional structures were investigated microscopically. Results The number of the layers of elastic fibers and medial SMCs of the Willis artery bifurcation were 1.5 ~ 12.6 and 1.1 ~ 9.0 respectively. And 70.6% of the embryos and 30.3% of the specimen were disclosed the local defects of the medial SMCs at the bifurcations of the developing arteries. Conclusions The number of the layers of elastic fibers and medial SMCs in fetal brain arteries increases with age. The congenital anomaly of the elastic fibers and SMCs are proved by this experiment, supporting a possible pathogenesis for intracranial vascular aneurysms.