Immunohistochemical identification of prolactin-producing cells in pituitary isografts in CBA mice.

Prolactin producing cells were investigated in pituitary isografts placed from female donor to female host CBA mice and also in the in situ pituitary gland of the graft-bearing host mice. Prolactin-producing cells were identified immunohistochemically using anti-mouse prolactin serum. Light microscopically, the cells with immunoreactive prolactin granules are present throughout the entire area of pituitary isografts, but less frequently in the in situ pituitary gland of the host mice. Electron microscopically, prolactin-producing cells may be classified into 3 types mainly based upon immunoreactive prolactin granules. Prolactin-producing cells in the pituitary grafts are classified as modified type III cells containing numerous immunoreactive prolactin granules resembling those found in the type III cells well-developed endoplasmic reticulum and enlarged Golgi apparatus. In contrast, following 5 d of the treatment with 2-bromo-alpha-ergocriptine, both type III and modified type III cells were decreased in number and type II cells were increased, and the cytoplasmic organella in these prolactin-producing cells appeared to be poorly developed.