Histochemical reactivity and staining properties of functionally defined cell types in the human adenohypophysis

Histochemical properties and histologic staining characteristics of a variety of procedures are delineated for the three types of adenohypophyseal mucoid cells whose function has been identified by immunostaining methods. Content of glycoprotein hormones may, in part, account for the periodic acid-Schiff (PAS) reactivity in the thyrotropic and gonadotropic but not the melanocorticotropic cell types. The melanocorticotropic cells evidence basophilia attributable to sialic acid residues, sulfate esters and possibly an additional unidentified component with atypical reactivity. The finding that basophilia of thyrotropic and gonadotropic cells appears largely attributable to sulfate esters indicates the presence of acid mucosubstance other than the glycoprotein hormone in these cells. The effect of oxidation in inducing basophilia indicative of cysteine- or cystine-rich protein varies in the different cell types. Melanocorticotropic cells alone among the mucoid group evidenced content of strongly basic protein, demonstrating stronger affinity for the acid dye Biebrich scarlet than the classic acidophils.