A general high-power photomicrograph, showing an essentially midsagittal section through the ovum. The decidual reaction about the ovum is moderately prominent. The outer syncytiotrophoblast has an irregular, intercommunicating, lacunar network containing maternal blood. The cytotrophoblast consists of an irregular inner shell, varying from a single layer of differentiated Langhans' epithelium to irregular masses of proliferating cells projecting into the syncytiotrophoblast constituting the primordia of chorionic villi.
Fig. 23. Hertig and Rock, 1941.
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Keywords: Langhans' epithelium, cytotrophoblast, decidual reaction, embryo, lacunar network, primordia of chorionic villi, syncytiotrophoblast
Source: The Virtual Human Embryo.