胎儿脑动脉分叉部中层平滑肌细胞的结构特点

Structural features of the smooth muscle cells in the medial layer of the bifurcation of fetal cerebral arteries

目的探讨人类胚胎脑动脉分叉部中层平滑肌细胞(smooth muscle cell,SMC)的构筑发育过程及特点.方法收集12～28周人类胚胎共17例,胎龄各相差1周,男女不限.对不同胎龄胚胎Willis环周围的脑动脉分叉部行三维组织切片,观察中层SMC的构筑发育过程及其有无先天缺陷.结果胎儿Willis环周各脑动脉中层SMC在1.1～9.0层之间;70.6%的胎儿在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.结论胎儿脑动脉中层SMC随胎龄增长而增多,但28周内不超过9.0层;本研究发现胎儿脑动脉分叉部存在先天性SMC缺陷.这将有助于对脑动脉瘤病因假说的理解和验证.

Objective To studythestructuralandhistogeneticfeaturesof thesmoothmusclecells(SMCs)in themediallayer of thebifurcationof humancerebralarteriesin fetus.Method Segmentsof thecerebralarteriesfromthecircleof Willis includingthe bifurcationsof normalhumanfetusesweresectionedin1of the3orthogonalplanes,whereinthe three-dimensionalmediallayerstructurecomposedof SMCswasobservedwithlightmicroscope.Result Microscopicobservation identified1.1to9.0SMClayersinthemediallayerof thecerebralarteriesfromthecircleof Willisin thefetusesat different weeksbeforebirth,and30.3%of thespecimenswerefoundto havefocaldefectsof themedialSMClayersat thebifurcation of thedevelopingarteries.Conclusion The numberof SMC layersconsistedin themediallayersof thecerebralarteries developswiththe fetalgrowth,and the identificationof congenitalanomalyof the medialSMCs may helpverifythe hypotheticalpathogenesisforcerebralsaccularaneurysms.