the present study therefore determined the ability of the rat placenta to convert [ 3h ] pregnenolone ( p5 ) substrate to [ 3h ] delta 4 a and [ 3h ] t , and to [ 3h ] progesterone ( p4 ) in vitro on days 12 , 14 , 16 and 18 of gestation .
C0033308
progesterone
C0032961
gestation