不同切变应力区动脉内皮细胞形态的扫描电镜观察

动脉粥样硬化(AS)好发于动脉的特殊部位,如动脉的分叉或弯曲处,从血流动力学观点来看,这是与这些部位的不同切变应力有关。我们采用20个样本进行扫描电镜观察,结果表明:(1)低切变应力区(主动脉弓腹侧或腹主动脉叉外侧壁)内皮细胞呈多形而不规则,排列无序,细胞表面多绒毛且连接紧密。(2)高切变应力区(主动脉弓背侧或腹主动脉叉内侧壁)内皮细胞呈“梭形”,排列与血流轴流方向一致,细胞表面较少绒毛且可见细胞间隙,在某些较大“峡谷”样间隙处见到大量胶原纤维。因此高切变应力区内皮细胞损伤大于低切变应力区。

SCANNING ELECTROMICROSCOPY OF ARTERIAL ENDOTHELIAL CELLS AT AREAS OF DIFFERENT SHEAR STRESS

Atherosclerosis (AS) is usually preferentially located at certain parts of arteries, for example at bifurcation or bending part of artery. Some hemodyna-mists believe that this predilection of AS is due to the difference in shear stress in there areas. We observed 20 specimens (each 0.5cm long) under the scanning electromicroseopy. The results were: (1) Areas of low shear stress, on the ventral wall of aortic arc and lateral wall of bifurcation of the abdominal aorta, endothe-lial cells appear polymorphous and irregular and the cells are arranged randomly. There are many microvilli on the cells surface and there are tight connections between two cells. (2) In areas of high shear stress as the dorsal wall of aortic arc and medial wall at the bifurcation of the abdominal aorta, the morphology pf the endothelial cells are "Shuttle Shaped". The orientation of the cells coincide with the direction of blood flow. There are very few microvilli on the cells surface. Integrity of these cells is poorer than that of the above group. The intercell space were wider. Some areas show large "valley" like fissures. A lot of collagen fibers can be seen in the "valley". This results show that endothelial demage in the areas with high shear stress is greater than in areas with low shear stress and resulting in further development of AS.