AN ULTRASTRUCTURAL-STUDY OF EPITHELIUM DIFFERENTIATION IN THE HUMAN FETAL FALLOPIAN-TUBE

The epithelial structure of the developing human fetal Fallopian tube has been studied systematically by parallel light, transmission and sc anning electron microscopy. The specimens for this study were collecte d from spontaneous abortions at the 14th, 18th, 20th and 22nd weeks an d from cases of intrauterine fetal death at the 24th and 31st weeks (h ydrocephalus). The epithelium lining the wall of the female genital du cts was pseudostratified in a columnar fashion. It consisted of differ entiating ciliated and microvillous cells and some degenerating elemen ts. Microvillous cells - by far the most abundant in the early phases of tubal development - often showed a solitary cilium. Ciliated elemen ts, though always less numerous than microvillous cells, were more den sely concentrated on the developing fimbriae and at the uterotubal jun ction than in the ampulla. On the mucosal surface of the same regions, rounded intercellular holes delimited many crypts, from which ciliate d elements sometimes sprouted. Notable aspects of cell proliferation a nd ciliogenesis were commonly observed and are likely to be related to circulating estrogens. These ultrastructural data indicate that the t ypical pattern of the adult oviduct is already sketched in fetal life. Furthermore, a strategic gathering of cilia was noted primarily at th e sites of the developing oviduct, which will serve to mediate the pas sage of sperm and/or ova and promote fertilization in adult life.