Corticotropin-releasing hormone-like axons in the adrenal glands of fetal and postnatal sheep

The presence of corticotropin-releasing hormone outside of the brain suggests that it may have functional roles besides the stimulation of pituitary adrenocorticotropin. The purpose of the present study was to determine immunohistochemically, the ontogeny of corticotropin-releasing hormone-like immunoreactivity in sheep adrenals from fetal day 100 to adult. Adrenal corticotropin-releasing hormone-like immunoreactivity: 1) was found in all animals examined, 2) existed as clusters of darkly beaded axon-like fibers over medullary cells at the medullary-cortical interface or over islands of medullary cells surrounded by cortex or rays of medullary cells extending into the cortex, 3) showed a definite increase with age, 4) was depleted in newborns < 12 h old, and 5) was found in pre- and postnatal splanchnic nerves. In conclusion, corticotropin-releasing hormone-like immunopositive fibers are present in the ovine adrenal medulla at various stages of development, supporting the concept that corticotropin-releasing hormone in pre- and postnatal sheep may play a direct local part in the regulation of adrenal function.