Ishikawa H
Arch Histol Jpn. 1985 Apr;48(2):183-97. doi: 10.1679/aohc.48.183.
Both the development of red pulp and hemopoietic activity in spleen obtained from 62 human embryos and fetuses between 30 days and 20 weeks after ovulation were investigated light and electron microscopically. The spleen develops in the left-posterior portion of the dorsal mesogastrium at 35-40 days after ovulation. At the 8th week after ovulation, reticular cells formed a three-dimensional meshwork. Two types of reticular cells (dark and clear reticular cells) were observed in the splenic cord in the 12-13th week after ovulation. Mature hemopoietic cells, mostly of the erythroblastic series, increased in number in the extravascular spaces with the development of the fetus. However, presumptive hemopoietic stem cells or "undifferentiated mononuclear cells" (Fukuda, 1973a) did not appear in the spleen. Moreover, immature hemopoietic cells such as proerythroblasts, myeloblasts and megakaryoblasts could not be detected. Therefore, despite the occurrence of a well-developed reticular cell network, hemopoiesis was judged to have not taken place in human fetal spleen. Macrophages appeared in the spleen at the 8th week after ovulation and increased in number with the the development of the fetus. Phagocytosis of decrepit blood cells proved to be an essential function of the spleen.
对62例排卵后30天至20周的人胚胎和胎儿脾脏的红髓发育及造血活性进行了光镜和电镜研究。脾脏在排卵后35 - 40天于背侧胃系膜的左后部发育。排卵后第8周，网状细胞形成三维网络。排卵后第12 - 13周，在脾索中观察到两种类型的网状细胞（暗网状细胞和明网状细胞）。随着胎儿发育，血管外间隙中成熟的造血细胞数量增加，主要是成红细胞系列。然而，推测的造血干细胞或“未分化单核细胞”（福田，1973a）未出现在脾脏中。此外，未检测到未成熟的造血细胞，如早幼红细胞、成髓细胞和原巨核细胞。因此，尽管出现了发育良好的网状细胞网络，但判断人胎儿脾脏中未发生造血。巨噬细胞在排卵后第8周出现在脾脏中，并随着胎儿发育而数量增加。衰老血细胞的吞噬作用被证明是脾脏的一项基本功能。
