RESUMO
PAP and ABC methods have been used to detect the Oxytocin-like (OXT-L) neurons in the hypothalamus of the rat and the results obtained were compared with the CT-HRP retrograde tracing study from the posterior pituitary to the hypothalamus by Ju et al. It was verified that the projections to the posterior pituitary came from the supraoptic nucleus, paraventricular nucleus, anterior and posterior fornical nucleus, perivascular cell groups, preoptic and anterior hypothalamic areas, the dorsal accessory cell groups, and the periventricular area, especially forming subependymal plexuses along the lateral wall of the third ventricle and beneath the interventricular foramen. By combining WGA-HRP retrograde tracing and immunohistochemistry methods, OXT-L neurons in all the above listed nuclei or cell groups were found to project to the posterior pituitary. The subependymal plexuses may serve as a link between the CSF in the ventricles and the posterior pituitary.