Fujiwara T, Iijima T
Laboratory Animal Center, School of Medicine, Ehime University, Japan.
Am J Anat. 1990 Nov;189(3):253-60. doi: 10.1002/aja.1001890308.
Arteriovenous anastomoses in the rabbit ear were examined with scanning electron microscopy to elucidate the structural differentiation of the media of the shunt. Arterial, intermediate, and venous segments in the shunt and two layers of the media in the intermediate segment were differentiated based on cell shape and cell organization. In the arterial segment, smooth muscle cells were spindle-shaped, either elongated or short, with a few branches, and were arranged circularly or diagonally with respect to the vessel's long axis. There were also stellate muscle cells with radiating processes. In the intermediate segment, the smooth muscle cells of the outer layer of the media were also arranged circularly and resembled the elongated cells in the arterial segments, but they were more irregular in shape and had more processes than those of the arterial segment. The epithelioid cells of the inner layer of the media were oval or polygonal and oriented irregularly with respect to the vessel's long axis, clustering to form longitudinal plicae. The smooth muscle cells of the venous segment were flat with many lateral processes and formed a thin, discontinuous layer. The smooth muscle cells in the arterial segment and those of the outer layer of the intermediate segment exhibited a highly rugged surface texture, indicating their strong contractility; the epithelioid cells and the smooth muscle cells in the venous segment exhibited a generally smooth surface, indicating less contractility. The intermediate segments were supplied with a dense nerve plexus. The intermediate segments, therefore, may be actively involved in the regulation of blood flow under neuronal influence.
利用扫描电子显微镜对兔耳的动静脉吻合进行了检查，以阐明分流通道中膜的结构分化。根据细胞形状和细胞组织，区分了分流通道中的动脉段、中间段和静脉段以及中间段中膜的两层。在动脉段，平滑肌细胞呈纺锤形，有长有短，有少量分支，相对于血管长轴呈环形或斜向排列。还有带有放射状突起的星状肌细胞。在中间段，中膜外层的平滑肌细胞也呈环形排列，类似于动脉段的细长细胞，但它们的形状更不规则，突起比动脉段的更多。中膜内层的上皮样细胞呈椭圆形或多边形，相对于血管长轴排列不规则，聚集形成纵向皱襞。静脉段的平滑肌细胞扁平，有许多侧向突起，形成一层薄的、不连续的层。动脉段的平滑肌细胞和中间段外层的平滑肌细胞表现出高度粗糙的表面纹理，表明它们具有很强的收缩性；静脉段的上皮样细胞和平滑肌细胞表面一般光滑，表明收缩性较小。中间段有密集的神经丛。因此，中间段可能在神经影响下积极参与血流调节。
