Gonadotropin Secretion in Vitro by Human Pituitary Null Cell Adenomas and Oncocytomas**

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Abstract
Pituitary null cell adenomas and oncocytomas are tumors not associated with clinical or biochemical evidence of hormone excess; morphological studies have not hitherto revealed their origin or the nature of their hormone production, if any. We examined the in vitro secretory activity of seven null cell adenomas and five oncocytomas which caused symptoms of a mass lesion and variable degrees of hypopituitarism. All tumors were classified at the time of surgical resection using immunohistochemistry and electron microscopy. RIA revealed the presence of FSH, LH, and a-subunit of pituitary glycoprotein hormones in the culture medium of eight tumors, FSH and asubunit in the medium of one tumor, and TSH, FSH, LH, and α-subunit in the medium of three adenomas. Morphological examination of cultured tissues confirmed the presence of tumor cells resembling those in the initial surgical specimen. Thus, we conclude that null cell adenomas and oncocytomas contain cells that can produce pituitary glycoprotein hormones, and that the majority produce gOnadotropins.