Noguchi Y, Shibata Y, Yamamoto T
Anat Rec. 1987 Apr;217(4):355-60. doi: 10.1002/ar.1092170406.
Endothelial plasmalemmal vesicles were examined in serial sections and in deep-etch replicas of rapid-frozen rat muscle capillary endothelium. Numerous fused vesicles were observed in both preparations. The morphology of the vesicles in rapid-frozen capillaries differed from that in the chemically fixed ones; rapid-frozen vesicles were spherical rather than ovoid, and the necks of caveolae and the connecting portion of fused vesicles were wider than those of chemically fixed ones. In the serial sections, true free vesicles were rarely identified (1.6%). In the deep-etch replicas, some of the cytoplasmic surface of vesicles had a mulberrylike appearance and intracytoplasmic fine fibrils appeared to connect the vesicles either to other vesicles or to the plasmalemma proper. Two transendothelial channels were found among 250 capillary profiles. Almost all endothelial "vesicles" proved to be invaginations of the surface membrane, and chemical fixatives did not seem to induce any substantial membrane fusion. These observations suggest that transendothelial transport of large macromolecules across continuous capillary endothelium is carried out mainly by diffusion through transendothelial channels.
在连续切片以及快速冷冻的大鼠肌肉毛细血管内皮的深度蚀刻复制品中检查了内皮细胞质膜小泡。在这两种制备物中均观察到大量融合的小泡。快速冷冻毛细血管中小泡的形态与化学固定的毛细血管中的不同；快速冷冻的小泡呈球形而非卵形，小窝的颈部和融合小泡的连接部分比化学固定的更宽。在连续切片中，真正的游离小泡很少被识别（1.6%）。在深度蚀刻复制品中，一些小泡的细胞质表面呈桑椹状外观，并且细胞质内的细纤维似乎将小泡与其他小泡或与质膜本身相连。在250个毛细血管轮廓中发现了两个跨内皮通道。几乎所有内皮“小泡”都被证明是表面膜的内陷，并且化学固定剂似乎不会诱导任何实质性的膜融合。这些观察结果表明，大分子跨连续毛细血管内皮的跨内皮转运主要通过跨内皮通道的扩散来进行。
