Electron microscopic study of the human trophoblast in culture.

The human placenta is one of the most complex organs with multi-functions, i. e. transportation of water and metabolites between the maternal and fetal circulation, production of estrogen, progesterone and gonadotropins. The recent application of the investigative methods, tissue culture or electron microscopy other than light microscopy, to the human placenta has thrown more light on the functional correlation to the morphological details. Since initial contribution by Boyd and Hughes (1954), electron microscopic studies of the human placenta in various stages of pregnancy were done by Boyd and Hughes (1954), Wislocki and Dempsey (1955), Lister (1963), Rhodin and Terzakis (1962), Terzakis (1963) and Lister (1964). Ultrastructural characteristics of syncytioand cytotrophoblast have been defined. In addition, the concept of the intermediate or transitional type of trophoblast which is ultrastructural evidence of the formations of syncytiotrophoblast from the cytotrophoblast is due to the great contribution by the electron microscopy (Carter, 1964, Enders, 1965, and Boyd and Hamilton, 1966). On the other hand, studies on human trophoblast using tissue culture techniques have been carried out by some investigators (Gey, Seegar and Hellman, 1938, Soma, Ehrmann and Hertig, 1964, Thied, 1960, and Thiede and Rudolph, 1961). Notake et al. (1965) revealed three types of outgrowth pattern and changes in process of aging, and also Patillo et al. (1968) succeeded in continuous culture of human choriocarcinoma transplanted to the hamster cheek pouch. The localization of human chorionic gonadotropin in cultured trophoblast has been proved (Notake et al., 1965) and also Sawasaki et al., (1969) proved the existence of steroid hormone genesis in epithelioid cells.