Prolactin cells in the human pituitary. A quantitative immunocytochemical analysis

Sixty adult human pituitary glands taken at autopsy were stained for prolactin using the immunoperoxidase technique, and percentages of prolactin-bearing cells were assessed. There was no difference between the percentages of prolactin cells seen in the adenohypophyses of adult men and nulliparous women; they averaged 16.9%, with an average of from 8.6% to 31.3%. Percentages did not vary with age, and were higher in women in the perinatal period. In multiparous women percentages were increased, which indicates that prolactin cell hyperplasia of pregnancy does not completely reverse. No regression of prolactin cells was evident in the nontumorous portion of glands that harbored prolactinomas; however, percentages were elevated in glands with non-prolactin-producing adenomas. Quantitative adenohypophysial cell classification provides a basis for defining hyperplasia and abnormal distribution of cells that result from various pathologic conditions, drug therapies, and changes in the hormonal environment.