Figure 2.

Steroid biosynthesis in the developing primate fetus. Steroidogenic enzymes are represented by the following abbreviations: P450c17 (17 and α-hydroxylase and 17,20-lyase activities); 3 and β-HSD (3 and β-hydroxysteroid dehydrogenase activity); P450c11b1 (11 and α-hydroxylase activity); P450c11b2 (aldosterone synthase activity); P450arom (aromatase activity). The fetal zone of the fetal adrenal cortex is capable of performing the reactions in the shaded area. The overlapping box (right) represents estrogen biosynthesis by the placenta. A-dione, androstenedione