Development of Sinusoidal Wall in Human Fetal Liver: A Morphological Study on Endothelial Cells, Kupffer Cells and Transmural Migration of Erythropoietic Cells

The 5 cases of human fetal liver aged from 11 to 23 weeks of gestation were investigated for the ultrastructure of sinusoidal wall by electron microscopy. The endothelial cells deficient in basement membrane formed almost all the part of sinusoidal wall. The cells were continued with neighboring cells by intercellular junction, and overlapped them and exhibited to maintain unfenestrated capillary wall, which was different from those with fenestra in adults. The cells were found to have coated pits on luminal side and several various vesicles in the cytoplasms. The cells were related with transcellular migration of reticulocytes and acidophilic erythroblastes, which penetrated into the endothelial cytoplasm to form transient migrating pore closing after the migration into sinusoidal lumen. The perivascular cells were present at perivascular space and surrounding the sinusoid discontinuously. The Kupffer cells were easily identified with filipodia and lamellipodia and with phagosome of nuclei enucleated from acidophilic erythroblasts.