Cellular composition of the human pituitary pars tuberalis as revealed by immunocytochemistry

Summary An attempt was made to determine if any of the specialized secretory cell types common to the pars distalis also occur in the pars tuberalis of the human hypophysis. Available for study were 18 specimens of the inferior pars tuberalis, which partially surrounds the infundibular stem, and 3 specimens of the superior pars tuberalis that is attached to the median eminence. Antisera to human somatotropin, mammotropin, chorionic gonadotropin, follicle-stimulating hormone, FSH , luteinizing hormone, LH , thyrotropin, TSH , as well as to ^1–24-corticotropin, porcine ^17–39-corticotropin, and ovine LH were used with the Sternberger peroxidase-antiperoxidase immunocytochemical procedure to identify the probable cells of origin for these hormones.The evidence indicated that gonadotropic cells constitute the major portion of the parenchymal cell population in the pars tuberalis. They occurred throughout all of the pars tuberalis and were usually arranged in clusters. Somatotropic, mammotropic, corticotropic, and thyrotropic cells were rare and not found in all specimens. When present, they often formed a common group suggesting that their occurrence in the pars tuberalis resulted from displacement of primordial tissue of the pars distalis during embryogenesis.Supported in part by research grants HD-03159 and HD-08333 from the National Institute for Child Health and Human DevelopmentWe thank Dr. L.A. Sternberger for providing the PAP complex and others for antisera (Table 2) and hormones (Footnote 2) as listed