[Expression of cytochrome P450scc in human early placenta]

The present study has determined the cellular distribution of cytochrome P450scc in human early placenta by immunohistochemistry and assessed the abundances of cytochrome P450scc protein in the villous tissue at 6-9 weeks of human pregnancy by Western blotting. The results showed that immunoreactive P450scc was mainly localized in the villous syncytiotrophoblast cells but not in the cytotrophoblast cells and the villous core, and that the expression of protein for cytochrome P450scc in human early placental villous tissues increased gradually with advancing weeks of pregnancy. Taken together, these findings suggest that the syncytiotrophoblast cells are the major site expressing P450scc in human early placenta, and that increasing expression of cytochrome P450scc in placental villi might establish a foundation, in terms of enzymology, for site-shift of progesterone biosynthesis from the corpus luteum to the placenta during human early pregnancy.