Localization of prolactin within the pituitary of a cyprinodont fish, Fundulus heteroclitus (Linnaeus), by specific fluorescent antiovine prolactin globulin

Abstract

Precipitin reactions in vitro have shown that antibody to ovine prolactin is capable of binding ovine prolactin and a prolactin-like fraction prepared from the pituitary glands of the carp ( Cyprinus carpio) and the pollack ( Pollachius virens). It seems reasonable to postulate that it would also bind prolactin of other teleosts. Hence the globulin fraction of antiovine prolactin serum was bound to fluorescein isothiocyanate, purified, and the antibody solution used to localize prolactin within sections of frozen pituitary of Fundulus heteroclitus. Sections so prepared show the presence of green fluorescent antigen-antibody complex only in the acidophils of the rostral pars distalis. Control staining with fluorescent normal globulin failed to give this result. Serial sections adjacent to the fluorescent antibody-treated preparaions were stained histologically and the erythrosinophilic eta cells identified as those which contain prolactin. Since no other cells of the pituitary gave these reactions it can be concluded that the eta cells are the prolactin cells. Similar preparations from the pituitaries of fresh water adapted fundulus show that in the enlarged rostral zone the erythrosinophilic eta cells contain prolactin.