Frank R N, Turczyn T J, Das A
Kresge Eye Institute, Wayne State University School of Medicine, Detroit, Michigan 48201.
Invest Ophthalmol Vis Sci. 1990 Jun;31(6):999-1007.
We performed electron microscopic morphometric analyses on capillaries from macular and peripheral retinas of five adult cynomolgous monkeys and three elderly human subjects. Measurements from the monkey retinal capillaries were compared to those made on capillaries from frontal, temporal, parietal, and occipital cerebral cortex of the same animals. We measured the percent coverage of the endothelial lining of the capillaries by pericyte processes, as well as the ratio of the cytoplasmic areas of pericytes and endothelial cells. In addition, we compared the thickness of the capillary basement membranes in three regions: overlying pericytes; overlying endothelial cells; and interposed between pericytes and endothelial cells. In both monkey and human retinas, pericyte processes covered greater than 85% of the circumference of the capillary endothelial tube, whereas pericyte coverage of monkey cerebral capillaries was highly significantly (P less than 0.001) less than that of capillaries in either the macular or peripheral retina. The ratio of pericyte to endothelial cell cytoplasmic areas also was lower in the monkey cerebral cortex than in the retina, though the statistical significance was less than that of the length measurements. In all tissues measured, both from monkeys and humans, the portions of the capillary basement membranes interposed between pericytes and endothelial cells were highly significantly (P less than 0.0001) thinner than the regions of capillary basement membranes covering pericytes and endothelial cells. Considering functions that have been proposed for pericytes, these measurements suggest that regional control of microcirculatory flow and of blood-tissue barrier integrity, as well as control of endothelial cell proliferation, should be much greater in the retina than in the cerebral cortex. Thinner basement membranes between pericytes and endothelial cells may permit more cell membrane contacts between these cells, thus facilitating such control.
我们对5只成年食蟹猴和3名老年人类受试者的黄斑区和周边视网膜的毛细血管进行了电子显微镜形态计量分析。将猴视网膜毛细血管的测量结果与同一动物额叶、颞叶、顶叶和枕叶大脑皮质毛细血管的测量结果进行比较。我们测量了周细胞突起覆盖毛细血管内皮衬里的百分比，以及周细胞和内皮细胞的细胞质面积比。此外，我们比较了三个区域的毛细血管基底膜厚度：覆盖周细胞的区域；覆盖内皮细胞的区域；以及介于周细胞和内皮细胞之间的区域。在猴和人类视网膜中，周细胞突起覆盖了毛细血管内皮管周长的85%以上，而猴脑毛细血管的周细胞覆盖率显著低于黄斑或周边视网膜毛细血管的覆盖率（P<0.001）。猴大脑皮质中周细胞与内皮细胞细胞质面积的比值也低于视网膜，尽管统计学显著性低于长度测量结果。在所有测量的组织中，无论是猴还是人类，介于周细胞和内皮细胞之间的毛细血管基底膜部分都比覆盖周细胞和内皮细胞的毛细血管基底膜区域薄得多（P<0.0001）。考虑到已提出的周细胞功能，这些测量结果表明，视网膜对微循环血流和血组织屏障完整性的区域控制，以及对内皮细胞增殖的控制，应该比大脑皮质更强。周细胞和内皮细胞之间较薄的基底膜可能允许这些细胞之间有更多的细胞膜接触，从而促进这种控制。
