COMPARATIVE STEREOLOGICAL STUDY ON ZONATION AND CELLULAR COMPOSITION OF ADRENAL-GLANDS OF NORMAL AND ANENCEPHALIC HUMAN FETUSES .1. ZONATION OF THE GLAND

Comparative stereological studies were performed on zonation of adrena l glands in 10 anencephalic and 11 normal fetuses, aged between 24 and 39 postovulatory weeks. The development of adrenal fetal zone (FZ) is the main factor responsible for normal adrenal gland growth during th e intra-uterine life. At the end of fetal period volume of this zone a ttains over 8200 mm(3) and constitutes 69-70% of the total gland volum e, while respective values for zona glomerulosa (ZG), zona fasciculata (ZF) and medulla (M) are 1665 mm(3) (14%), 833 mm(3) (7%) and 1071 mm (3) (9%). These data were in striking contrast with those found in adr enals of anencephalic fetuses, in which volume of the gland attained o nly ca 35% of that in normal fetuses. In the oldest anencephalic fetus studied (39 weeks) the volume of the fetal zone was 962 mm(3) (ca 8-f olds lower than in normal fetus) comprising only 25% of the total glan d volume. For the remaining zones the values were: ZG - 1501 mm(3) (ca 90% of the normal value and 39% of the total gland volume); ZF - 770 mm(3) (ca 92% and 20% respectively), and M - 539 mm(3) (ca 50% and 14% , respectively). This stereological study provides the first systemic description of the development of adrenal gland of anencephalic fetuse s in comparison with the normally developing gland. Moreover, evidence is given that the growth of adrenal medulla is also retarded in anenc ephaly while the growth of the zona glomerulosa remains rather unaffec ted.