CORTICOTROPIN-RELEASING HORMONE-LIKE AXONS IN THE ADRENAL-GLANDS OF FETAL AND POSTNATAL SHEEP

The presence of corticotropin-releasing hormone outside of the brain s uggests that it may have functional roles besides the stimulation of p ituitary adrenocorticotropin. The purpose of the present study was to determine immunohistochemically, the ontogeny of corticotropin-releasi ng hormone-like immunoreactivity in sheep adrenals from fetal day 100 to adult. Adrenal corticotropin-releasing hormone-like immunoreactivit y: 1) was found in all animals examined, 2) existed as clusters of dar kly beaded axon-like fibers over medullary cells at the medullary-cort ical interface or over islands of medullary cells surrounded by cortex or rays of medullary cells extending into the cortex, 3) showed a def inite increase with age, 4) was depleted in newborns < 12 h old, and 5 ) was found in pre- and postnatal splanchnic nerves. In conclusion, co rticotropin-releasing hormone-like immunopositive fibers are present i n the ovine adrenal medulla at various stages of development, supporti ng the concept that corticotropin-releasing hormone in pre- and postna tal sheep may play a direct local part in the regulation of adrenal fu nction.