[The ultrastructure of human pituitary adenomas (author's transl)]

34 pituitary adenomas were examined by light and electron microscopical methods. Slices of tumor tissue fixed in formaldehyde or Bouin's solution, respectively, and embeded in paraffin were stained by hematoxylin-eosin, Goldner's method (including Orang G), periodic acid Schiff (PAS) reaction, and in some cases by Herlant's tetrachrom. The ultrastructure was studied using tumor tissue fixed in glutaraldehyde within 1 hour after removal. The adenomas were classified by their light microscopical characteristics as chromophilic or chromophobe tumors. Employing the PAS reaction and Goldner's staining method, 27 adenomas were found to give intense or weak staining reactions. By electron microscopical investigation , all the adenomas studied were seen to contain secretory granules more or less densely packed within the cytoplasm. The number of these granules was strongly correlated with the intensity of the tinctorial properties of the tumor tissue. Out of 11 acidophilic adenomas, 10 were observed consisting of typical STH cells. 4 acromegalic patients were found to possess heavily or poorly granulated STH cell adenomas (two patients in each of these groups). One patient with a clinical history of liver cirrhosis and gynecomastia was observed bearing an acidophilic (and erythrosinophilic) adenomatous hyperplasia of prolactin cells, 13 tumors consisted of cells exhibiting almost weak amphophilic staining properties and secretory granules of 100-250nm diameter, thus resembling cells which have been reported to produced ACTH. One of the patients suffering from these adenomas, showed the clinical signs of M. Cushing. By ultrastructural criterions, 3 adenomas with PAS-positive tumor cells were considered to be composed of gonadotropic cells. Only 7 adenomas were observed which did not give any chromophilic reaction. These tumors consisted of extreme poorly granulated cells which could not be significantly associated with one of the pituitary hormones by their morphological properties. In respect of the abundance of mitochondria, 4 out of the adenomas were designated as oncocytic tumors.