Effect of hypophysectomy on the growth and development of the sheep adrenal gland: a morphometric study.

We have investigated the effect of gestational age and fetal hypophysectomy on the growth and development of the adrenal gland of the fetal sheep. The area of the fetal sheep adrenal medulla increased significantly (P less than 0.05) from 3.21 +/- 0.42 mm2 at 90-107 days to 6.09 +/- 0.26 mm2 at 120-126 days of gestation and there was a further significant increase (P less than 0.05) in the newborn period to 9.48 +/- 0.85 mm2. The adrenomedullary area of the hypophysectomised fetal sheep (7.47 +/- 1.10 mm2) was not significantly different from that of the fetal sheep at 140-146 days of gestation or from that of the newborn lamb. The ratio of the area of the adrenal occupied by the cells which contained adrenaline (adrenaline zone) to the area of the adrenal occupied by the cells which contained noradrenaline (noradrenaline zone) was unchanged between 90 days of gestation and 12 days after birth. After hypophysectomy, the ratio of the adrenaline to noradrenaline zone was not significantly different from that in the adrenal medulla of the 140-146 days fetal sheep and the 10-12 days newborn lamb.