Sibley C P, Bauman K F, Firth J A
Cell Tissue Res. 1982;223(1):165-78. doi: 10.1007/BF00221507.
Haem proteins of different molecular sizes were perfused into the foetal circulation of the guinea-pig placenta to study the permeability of the foetal endothelium. The smallest molecules tested, microperoxidase (ae 1.0 nm) and cytochrome C (ae 1.5 nm), readily penetrated the endothelium; tracer-reaction product was found in the subendothelial space of the capillaries. However, there was no uptake of these two tracers into the syncytiotrophoblast layer of the placenta. An intermediate-sized molecule, myoglobin (ae 1.7 nm) produced only a weak reaction product in the subendothelial space even when perfused at high concentration. The largest molecule tested, haemoglobin (ae 2.8 nm), did not penetrate the foetal endothelium at any of the concentrations employed. The foetal capillary endothelium thus provided a barrier to protein penetration from the foetal circulation, dependent on molecular size. There was evidence that the site of this barrier was located in the lateral intercellular spaces between the endothelial cells. The syncytiotrophoblast of this haemomonochorial placenta provided an almost absolute barrier to protein penetration from the foetal circulation. As other workers have described maternal-to-foetal transmission of proteins across this layer in the guinea-pig, a working hypothesis of the role of endothelium and syncytiotrophoblast in maternal/foetal protein exchange is discussed.
将不同分子大小的血红素蛋白灌注到豚鼠胎盘的胎儿循环中，以研究胎儿内皮的通透性。所测试的最小分子，微过氧化物酶（约1.0纳米）和细胞色素C（约1.5纳米），很容易穿透内皮；在毛细血管的内皮下间隙发现了示踪反应产物。然而，这两种示踪剂没有被胎盘的合体滋养层摄取。中等大小的分子，肌红蛋白（约1.7纳米），即使在高浓度灌注时，在内皮下间隙也只产生微弱的反应产物。所测试的最大分子，血红蛋白（约2.8纳米），在所使用的任何浓度下都没有穿透胎儿内皮。因此，胎儿毛细血管内皮对来自胎儿循环的蛋白质渗透形成了屏障，这取决于分子大小。有证据表明，这个屏障的位置位于内皮细胞之间的侧向细胞间隙中。这种血绒毛膜胎盘的合体滋养层对来自胎儿循环的蛋白质渗透提供了几乎绝对的屏障。由于其他研究人员描述了豚鼠中蛋白质通过这一层从母体向胎儿的转运，本文讨论了内皮和合体滋养层在母/胎蛋白质交换中作用的一个可行假说。
