An immunohistochemical study of epithelial cells in the posterior lobe and pars tuberalis of the human adult pituitary gland.

Pituitary glands were examined using reference staining (hematoxylin and eosin, periodic acid-Schiff and alcian blue) and the peroxidase-labeled antibody method, for 1) "invading" anterior cells in the posterior lobe, 2) intermediate colloid forming follicles, and 3) pars tuberalis cells. The results showed: 1) that the majority of cases possessed "invading" anterior cells of various amount. Most of these cells were positive for ACTH1-18, ACTH17-39 and betaMSH. However, on a few occasions, scattered GH, PRL, FSHalpha, FSHbeta, LHbeta and even TSHbeta cells were also present. 2) Colloid forming follicular cells were mostly ACTH cells, but also contained occasional other hormone-secreting cells. Hormone negative cells were correlated with salivary type epithelium. Well established acinic type salivary glands and ciliated epithelium were negative for any hormones immunohistochemically. 3) Pars tuberalis cells were predominantly gonadotrophs but also included TSHbeta and ACTH cells. Some cells appeared to contain both FSHbeta and LHbeta. When these cells underwent squamous metaplasia, they seemed to lose their hormone secreting activity.