Morphologic features of the anencephalic adrenal gland in early pregnancy.

The adrenal glands of 12 anencephalic fetuses and 17 normal fetuses of 11 to 21 weeks' gestation were examined histometrically. The volume of the adrenal gland occupied by the fetal zone in the anencephalic fetuses was 57.5% compared with 76.5% in normal fetuses. The fetal zone in anencephaly showed involution in all specimens, which suggests that this involution begins well before 20 weeks' gestation.