Estrogen Uptake Capacity of Individual Pituitary Cell Types from Male and Female Rats One, Fourteen and Fifty Days after Castration

A quantitative autoradiographic technique was combined with immunocytochemical staining to compare 3H-estrogen uptake in individual pituitary cell types 1, 14 or 50 days after castration in both male and female rats. Silver grains were counted over nuclei of immunocytochemically stained cells and means were computed for each cell type. The order of labelling intensity for all groups was gonadotropes greater than or equal to lactotropes = somatotropes greater than thyrotropes = corticotropes. In male rats 3H-estrogen uptake capacity in all of these cell types remained unchanged over the post-castration interval. Only gonadotropes from female rats demonstrated a significant change in estrogen uptake capacity over the intervals examined. Uptake in these cells increased by 137% between 1 and 50 days after ovariectomy. At both 14 and 50 days post-ovariectomy, gonadotropes concentrated significantly more radioactive label than either lactotropes or somatotropes. One day after castration, gonadotropes from females concentrated less 3H-estrogen than males while at 50 days after castration they concentrated significantly more than gonadotropes from male rats.