Comparative-immunohistochemical study of the mammalian pituitary corticotrophs.

To investigate the distribution, shape and stainability of the ACTH cells from human, baboon, monkey, cat, dog, rat, mouse, hamster, guinea pig, white-toothed shrew, house musk shrew and mole pituitaries, adjacent tissue sections were immunostained with anti-porcine ACTH1-39 serum and with PAS-ironhematoxylin respectively. Mammalian ACTH cells display two separate morphological appearances :1) oval or polygonal and 2) stellate or elongate. The first type exists in all the tested mammals except for the house musk shrew, in which the elongate cells predominate. The second type co-exists with the first in the cat, dog, guinea pig, rat, mouse and hamster. Most ACTH cells were diffusely immunostained in all the mammals except for the rat and mouse, in which the rim of ACTH cells was immunostained. Based on their granularity, mammalian ACTH cells may be divided into oval or polygonal granule-rich chromophilic cells and into stellate poorly granulated chromophobic cells. The former can be classified into amphophilic and acidophilic subtypes according to their staining properties with PAS-iron-hematoxylin. Acidophilic ACTH cells are found in the dog, house musk shrew and mole ; amphophilic ones in the human, baboon, cat, mouse, hamster, white-teethed shrew and mole ; and chromophobic ones in the monkey, dog, guinea pig, rat and mouse.