title: Alpha-subunit-producing pituitary adenomas. Immunocytochemical and ultrastructural studies.
abstract: Immunohistological techniques demonstrate the alpha-subunit of glycoprotein hormones in the majority of endocrine-inactive, undifferentiated pituitary adenomas and pituitary oncocytomas. In about one-fifth of endocrine-active adenomas, the alpha-subunit is produced in combination with either adrenocorticotropic hormone or prolactin, and it is found in combination with growth hormone in about half of those adenomas causing acromegaly. Pure alpha-subunit-producing, endocrine-inactive adenomas characteristically have small secretory granules that are destroyed by direct osmium fixation, but are well preserved after prefixation with glutaraldehyde. As only a few atypical prolactinomas show similar secretory granules, and as they display a positive reaction for the alpha-subunit only exceptionally, this ultrastructural feature can serve as a guide to differentiate such adenomas.
mesh_terms: D000236:Adenoma / Q000378:metabolism*; D000324:Adrenocorticotropic Hormone / Q000378:metabolism; D006063:Chorionic Gonadotropin / Q000378:metabolism; D005260:Female; D015292:Glycoprotein Hormones, alpha Subunit; D006651:Histocytochemistry; D006801:Humans; D007120:Immunochemistry; D008297:Male; D008854:Microscopy, Electron; D010446:Peptide Fragments / Q000096:biosynthesis*; D010908:Pituitary Hormones, Anterior / Q000096:biosynthesis*; D010911:Pituitary Neoplasms / Q000378:metabolism*
chemical_list: D006063:Chorionic Gonadotropin; D015292:Glycoprotein Hormones, alpha Subunit; D010446:Peptide Fragments; D010908:Pituitary Hormones, Anterior; D000324:Adrenocorticotropic Hormone