Comparative Immunoelectron Microscopic Localization of Corticotropin-Releasing Factor (CRF-41) and Oxytocin in the Rat Median Eminence

Abstract

Comparative ultrastructural localization of corticotropin-releasing factor (CRF) and oxytocin was performec; in the rat median eminence of Long Evans and Brattleboro rats. The peroxidase-antiperoxidase technique used on seria. ultrathin sections revealed CRF and oxytocin neurosecretory granule colocalization in the same fibers of the internal layer running towards the posterior pituitary. It is probable that both these peptides coexist in the same granules. In the Brattle boro rats, while genetically lacking vasopressin, CRF was nevertheless shown to be present. In these rats, as was demon strated in the Long Evans rats, CRF distribution paralleled that of oxytocin only in the internal zone of the media! i eminence.