The identification of acidophilic cells in the human Pars distalis

Sections of human hypophyses were fixed in either formalin or Bouin's fluid and stained by a variety of acid stains. The stains were employed singly, in combination with each other and in conjunction with various mucoid staining procedures. After these procedures the chromophils of the pars distalis were classified as either acidophilic, mucoid, acidophilic‐mucoid, modified or degranulated. The remaining cells which lacked specific chromophilic granules were classified as chromophobes. The acidophils after the terminology of Ezrin were designated as cell types I, II and VIII which correspond to the alpha, eta and epsilon cells of Romeis. Numerous, carminophilic type I cells were present in glands of all ages. Although usually pyramidal or oval in shape they also exhibited a variety of morphologic forms. The type I cells were further subdivided into small, light and dark cells on the basis of size and nuclear characteristics. The type II cell although present in all glands was most frequently observed in fetal and post‐menopausal pituitaries. It was tinctorially identified by the prominent staining of its cytoplasmic granules with erythrosin. The type VIII cell exhibited staining properties intermediate between cell types I and II. On the basis of tinctorial and morphologic properties it was tentatively identified as a modified type I or type II cell.