The effect of age, pairing, copulation, and 2-Br-alpha-ergocryptine in the male Mongolian gerbil on the prolactin cells in the anterior pituitary identified by immunocytochemical and Herlant's tetrachrome methods.

Near-adjacent, midsagittal sections of pituitaries of infantile and adult male Mongolian gerbils in several experimental groups (bachelor, paired, tartaric acid-injected, postcopulatory gerbil, and postcopulatory animal injected with 2-bromo-alpha-ergocryptine [CB-154]), were stained by a modification of Herlant's tetrachrome and by the peroxidase-labeled antibody method for prolactin. Cell counts of erythrosinophils and cells immunoreactive for prolactin were made. Sequential staining procedures and thin adjacent sections were used to correlate the staining results. Erythrosinophils were very rare in the infant pituitaries; they increased (P less than .01) in numbers in bachelor pituitaries, remained at the same level (P greater than .05) in paired animals, increased (P less than .01) in the postcopulatory gerbils that were injected with tartaric acid, and increased much less (P less than .05) in postcopulatory males that were injected with CB-154. Prolactin cells were present in modest numbers in infant pituitaries; they increased (P less than .01); in bachelors and reached their highest number in paired animals (P less than .001); they remained unchanged (P greater than .05) in tartaric acid-injected postcopulatory animals but declined (P less than .001) in CB-154-injected, postcopulatory animals. The number of prolactin cells was always significantly greater (P less than .001) than the number of erythrosinophils. Correlative studies revealed the erythrosinophils, some of the light blue cells, and some of the chromophobes gave positive immunocytochemical reactions for prolactin. Apparently, CB-154 inhibited the erythrosinophils and the immunoreactive prolactin cells in the postcopulatory male gerbil, as indicated by a reduction in the number, size, and staining intensity of the cells.