An autoradiographic and immunocytochemical study of the neonatal rat pituitary gland.

Two-day-old female rats were injected with 5 nmole/kg of 6,7-3H-11 beta-methoxy-17-ethylestradiol (R 2858 = moxestrol) and killed one hour later. The animals were decapitated and, the pituitary glands were removed, mounted on tissue holders and frozen in liquified propane. The tissue was then processed for autoradiography according to the thaw-mount technique. At the end of the exposure time, prior to photographic development, some of the tissue was fixed in 10% formalin and then photographically developed for autoradiography. The fixed tissue was subsequently stained immunocytochemically using antibodies to luteinizing hormone or prolactin. Between 10 and 15% of the cells of the pars distalis concentrated the synthetic estrogen or its metabolite. The immunocytochemical procedure revealed that both LH-gonadotrophs and lactotrophs concentrated the steroid. These studies along with earlier studies suggest that the neonatal rat pituitary contains only a small portion of the adult complement of estrogen receptors and that these receptors are dispersed across a number of cell types.