Comparative localization of neurons containing ovine corticotropin releasing factor (CRF)-like and neurophysin-like immunoreactivity in the diencephalon of the pigeon (Columba livia domestica).

Neural elements immunoreactive for ovine corticotropin releasing factor-like immunoreactivity (oCRF-LI) were shown to be present in the diencephalon of the pigeon by using peroxidase-antiperoxidase immunocytochemistry. The external zone of the anterior median eminence contains a rich network of varicose oCRF-LI fibers in close proximity to the pituitary portal capillaries. Perikarya reactive for oCRF-LI were found in several regions known to innervate the median eminence and gave rise to axons which joined the hypothalamo-hypophyseal tract. A close topographical relationship between neurophysin-containing and oCRF-LI-containing neurons was found in anterior periventricular regions. These observations suggest that oCRF-LI material might be involved in the hypothalmic control of anterior pituitary hormone secretion in birds, and that neurophysin- and oCRF-LI-producing nerve cells might be functionally coupled.