[Morphology of the paraadenomatous adenohypophysis. A contribution to the pathogenesis of pituitary adenomas (author's transl)].

98 biopsies of the paraadenomatous adenohypophysis in acromegaly, galactorrhea combined acromegaly, isolated galactorrhea, hypothalamic-hypopphysial Cushing's disease. Nelson's syndrome, and in nonfunctional adenomas were studied by light microscopic methods in order to find evidence for a possible hyperplasiogenic origin of the different types of adenomas. It was hoped that the numerical relations and structures of hypophysial cells might provide significant information. Nodular ACTH cell-hyperplasia was found frequently apart from ACTH cell-tumors in Cushing's disease and Nelson's syndrome and on this basis we suggest that the adenomas in both diseases arise from hyperplasia. During their further development these adenomas seem to become autonomous, since the number of paraadenomatous ACTH cells decreased in bigger tumors. Some of the cases with isolated galactorrhea showed hyperplasia of acidophil and chromophobe cells in the paraadenomatous adenohypophysis. It can thus be assumed that porlactin cell-tumors also develop from prolactin cell-hyperplasia. Both the adenomas and the nonfunctional tumors in acromegaly seem to grow autonomously from the beginning, since paraadenomatous hyperplasia is seldom seen.