[Dynamics and significance of transferrin receptors in various human placental cell membranes].

It has been postulated that the process of iron transfer to the human fetus begins with the binding of maternal transferrin-iron complexes to placental transferrin receptors. This presentation deals with the dynamics of transferrin receptors on the cell membrane of trophoblastic cells including normal placenta cells, molar trophoblasts and choriocarcinoma cell lines (GCH-1, GCH-2, ENAMI). Results were as follows. Receptors for transferrin were observed on all the trophoblastic cell membranes tested. The transferrin receptors increased with the gestational weeks. Transferrin receptors on molar trophoblasts were approximately one-half to twice as numerous as those on normal trophoblasts. The transferrin receptors on choriocarcinoma cell lines were five to ten times as numerous as those on normal trophoblast. Thymidine uptake and native hCG secretion in choriocarcinoma cell lines increased with transferrin-iron addition to these mediums (but no increase in the beta-hCG secretion in the medium was observed). On the other hand, the transferrin receptors on these membranes decreased.