MAMMOSOMATOTROPES - PRESENCE AND FUNCTIONS IN NORMAL AND NEOPLASTIC PITUITARY TISSUE

More than a half century has passed since Romeis first proposed the “one cell-one hormone” theory which holds that each of the major pituitary hormones is produced by a separate and distinct cell type (1). Consistent with this idea, the acidophilic staining cells (termed acidophils) of the adenohypophysis have been traditionally subdivided into two categories, those that secrete only GH and others that produce just PRL. This view was supported by considerable tinctorial evidence available at the time of Romeis’ hypothesis and generated in the subsequent three decades (1–5). Moreover, data produced throughout the 1970s and early 1980s by the use of light microscopic immunocytochemistry (ICC) and immunofluorescence were generally consonant with the one cell-one hormone theory, except in the case of certain pituitary tumors (6–8). The presence of bihormonal acidophils in this latter situation was attributed to aberrant mechanisms attendant to the neoplastic condition. However, as will be discussed in detail later, the utilization of even newer techniques with greater powers of resolution and sensitivity has radically changed the unihormonal view of acidophil function. © 1991 by The Endocrine Society.