The hypothalamic magnocellular neurosecretory system of the guinea pig. I. Immunohistochemical localization of neurophysin in the adult.

With the use of the unlabeled antibody enzyme technique and antiserum against bovine neurophysin I, neurophysin was localized in the hypothalamic magnocellular neurosecretory system of the adult guinea pig. Immunoreactive deposits were found in the perikarya of the supraoptic and paraventricular nuclei, their fiber projections and terminals in the posterior pituitary. No parvicellular neurophysin-positive components were observed. In the median eminence neurophysin was seen in the zona interna where axons of the supraoptico-hypophysial tract pass on their way to the neural lobe. The peptide was also present in axons projecting into zona externa which terminate on the primary portal plexus.