Human pituitary corticotrophs: their amphophilic stainability and immunohistochemical characterization

Immunohistochemical characterization of the human pituitary beta(R) cells was investigated through the findings of the immunoreactivities with anti-porcine ACTH, -rat TSH, -rat FSH sera. Immunostained corticotrophs are oval or round in shape and localized in the anteromedial wedge. It is shown on the adjacent sections that they correspond to the beta(R) cells with amphophilic stainability with PAS-iron hematoxylin. In this wedge, amphophilic cells are preponderant, but PAS-positive thyrotrophs and gonadotrophs are not numerous. Amphophilic stainability varies in degree from cell to cell: One cell contains numerous medium-size of secretory granules weakly stained with iron hematoxylin and strongly with PAS in the PAS-positive cytoplasm, and the other cell is filled with big secretory granules intensively stained with iron hematoxylin and weakly with PAS. The immunostained TSH, LH and FSH cells are different from the beta(R) corticotrophs, because anti-ACTH serum never reacts to the TSH, LH and FSH cells in the two adjacent sections. LH and FSH reactivities are observed in the single cells. It is concluded that human corticotrophs are amphophilic beta(R) cells filled with secretory granules, and that they have quite a different appearance from the rat chromophobic stellate corticotrophs with a row arrangement of secretory granules along the plasma membrane.