An immunocytochemical staining technique was used to investigate the development of the sheep adrenal medullary cells containing enkephalins and the catecholamine synthetic enzymes dopamine beta-hydroxylase (DBH) and phenylethanolamine N-methyl transferase (PNMT). No staining was observed in the adrenocortical cells with any of the antisera used in this study. Positive staining with anti-DBH was observed throughout the medulla in both adult and fetal adrenal glands from 80 days of gestation. Positive staining with anti-PNMT was observed in all glands from as early as 80 days of gestation, and staining with this antiserum was mainly confined to the peripheral medullary cells, which were adjacent to, and interdigitated between, the cells of the adrenal cortex. In the fetus between 80 and 120 days of gestation, staining for the enkephalins was observed in both the peripheral columnar and the central polygonal adrenal medullary cells. After 125 days of gestation and in the adult ewe, the peripheral columnar cells were uniformly stained with anti-enkephalin whereas many unstained cells were present in the central medullary region. Therefore, enkephalin-containing peptides are present in the catecholamine cells of the fetal and adult sheep adrenal and there appears to be a changing pattern in the distribution of the enkephalins in the fetal adrenal in late gestation.

We have investigated the effect of fetal hypophysectomy on the localization of dopamine B-hydroxylase (DBH), phenylethanolamine N-methyltransferase (PNMT) and enkephalin-containing peptides in the fetal sheep adrenal, using immunocytochemical techniques. Staining with anti-DBH was observed throughout the adrenal medulla in the intact (140-146 days of gestation) and hypophysectomized fetal sheep (147-164 days of gestation) and the newborn lamb (10-12 days after birth). In the adrenal medulla of the late-gestation intact fetal sheep and newborn lamb, positive staining with anti-PNMT was observed in the peripheral rim of medullary cells adjacent to the adrenal cortex. After hypophysectomy, there was intense positive staining with anti-PNMT in the peripheral adrenal medullary cells and a small and variable proportion of central adrenal medullary cells were stained with anti-PNMT. In the adrenal gland of the intact fetal sheep and the newborn lamb, there was intense staining with anti-enkephalin in the peripheral rim of adrenal medullary cells. Staining with anti-enkephalin was less intense in the central medullary cells of the adrenal gland of the intact fetal sheep and the 10- to 12-day-old newborn lamb, and many unstained central medullary cells were present. After hypophysectomy, intense positive staining with anti-enkephalin was observed throughout the entire fetal adrenal medulla. Therefore, the fetal pituitary, either directly or indirectly through the adrenal cortex, plays a role in regulating the pattern of localization of both PNMT and enkephalin in the fetal sheep adrenal.

No abstract