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, I1 and VIII which correspond to the alpha, e ta 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 I1 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 11. O n the basis of tinctorial and morphologic properties it was tentatively identified as a modified type I or type I1 cell. Prior to a study of pituitary cytogenesis the literature was searched for previous descriptions of pituitary cell types and the methods utilized for their demonstration. It was soon apparent from this literature survey that a great deal of confusion existed about the type and function of pituitary cells and the specificity of staining methods employed (see reviews : Purves, '61; Halmi, '63; Ezrin, '64; and Herlant, '64). Factors which apparently contributed to this confusion were : ( 1 ) the utilization of selective but not specific staining methods to study glands from different species, (2) a lack of adequate morphological descriptions of specific cell types, ( 3 ) a lack of consistency in the use of nomenclature and (4) overemphasis an the correlation between cell types and concomitant endocrine disorders. Presumably, less confusion would have occurred if certain guidelines common to all cytological studies had been observed. Some of the more significant of these are: ( 1 ) cells of different species which have the same tinctorial properties may not necessarily have the same function; (2) morANAT. REC., 156: 347-360. phologic parameters are variable and dependent on the physiological state of the cells; ( 3 ) cells that secrete specific hormones that are chemically consistent can be expected to exhibit consistent histochemical properties in spite of morphologic variability. In order to clarify the cytology of the human pars distalis,2 sections were examined after the application of a variety of histological and histochemical procedures. The specificity of the methods was evaluated and the chromophils of the normal human hypophysis were identified. Additionally, the histochemical cytology of the gland was compared with the published immunocytologic descriptions. The present report deals with a description of acidophils and chromophobes, while a subsequent report will describe the hypophyseal mucoid cells. For the sake of brevity and in observance of the above criticisms, only limited reference is made to studies of the hypophysis of other species. 1 Research supported by grant HD 00557 from National Institute of Child Health and Human Devclopment, National Institutes of Health. ZThe term pars distalis is employed as defined by Purves and Bassett ('63) and is homologous to the pars anterior and pars intermedia of most species.