Regulation and function of steroid production by mid gestation ovine fetaladrenal cortex in vivo.

By mid-gestation (75-85 days, term=150 days), the ovine fetal adrenal gland is zoned into cortex and medulla. The cortex has an outer layer of cells w hich have the morphological characteristics of zona glomerulosa cells, cont aining mitochondria with lamellar cristae. It has been reported that cultur ed adrenal cells from mid-gestation bovine and ovine fetuses can be stimula ted to increase aldosterone production, ten fold, by angiotensin II, and th at this can be maintained for at least 3 days. However, the situation in vi vo is unknown. In the current report we show that in chronically cannulated ovine fetuses at mid-gestation, angiotensin II (1 mu g/h) does not increas e aldosterone either in the short term (3 hours) or long term (3 days). How ever, ACTH (450 ng/h) can increase plasma aldosterone in the short but not long term. ACTH at this dose produces progressive and large increases in co rtisol production. Angiotensin II is presser and produces a modest diuresis without stimulating cortisol.