Steroid metabolism of foetal tissues. I. Metabolism of pregnenolone-4-14C by human foetal ovaries.

The metabolism of pregnenolone-4-14C of ovaries from human foetuses ranging in age from the 14th through the 42th week of gestation was studied by a double isotope method in vitro. Progesterone was found as the main metabolite. The rate of conversion is correlated with histochemical findings of the same material and comparison with the FSH- and LH-concentration in human foetal pituitaries is made. As further metabolites only 17alpha-hydroxypregnenolone and dehydroepiandrosterone were isolated. For comparison tissue from a polycystic ovary was investigated with the same method.     

Transglutaminase activity and embryonal carcinoma cell differentiation

Murine embryonal carcinoma (EC) cells induced to differentiate by retinoic acid (RA) modulate transglutaminase (TGase) activity shortly after exposure to the inducer. Compounds that inhibit TGase enzyme activity in vitro can successfully block RA induced EC cell differentiation in culture. These observations suggest that TGase may play a role in mediating RA induced EC cell differentiation.