LAUSR

A method is described for isolation of relatively large quantities of large and small hormone storage granules from the beef adenohypophysis. The hormone storage granules are highly purified, as indicated by ultrastructural and biochemical criteria. The average size of large granules is 400 mg and of small granules is 220 m. The large granules contain growth hormone and prolactin; the small granules contain high concentrations of follicle-stimulating, luteinizing, and thyroid-stimulating hormones. An alkaline protease with a pH optimum of 8.3 is associated with the small granule fraction. Evidence accumulated in the last twenty years indicates that the six known hormones of the adenohypophysis are contained in separate and distinct cell types (1-4). The acidophilic cells in the rat and mouse pituitary synthesize and store somatotropin and prolactin (5-8). The basophilic cells produce thyrotropin and two gonadotropins (9-12). The host cell responsible for production and storage of corticotropin is still uncertain. Ultrastructurally these cell types differ mainly in the size of their storage granules. In the rat adenohypophysis the acidophilic cells contain large storage granules with a diameter of 350600 my (7), whereas the granules of the basophils are much smaller, their diameter ranging from 140-200 mp (4, 9). Several attempts have been made to isolate the storage granules of the adenohypophysis (15-18). However, only McShan and his group have succeeded in preparing from the rat adenohypophysis a large granule fraction and a small granule fraction relatively free of contamination by other subcellular structures (13, 14). The study reported here is part of a continuing investigation of the structural components in various storage granules. Since the yield of purified granules from the rat pituitary is necessarily limited, we have attempted to isolate the small and large storage granules from bovine adenohypophysis. Initially we used the method developed by McShan et al. (13, 14). However, it soon became apparent that this procedure was not suited to beef pituitary without extensive modification. In this communication we describe fractionation procedures suitable for the isolation of a large and a small granule fraction from the bovine adenohypophysis. The electron microscopic, biochemical, and biological studies indicate that these fractions are highly purified. The lipid and protein composition and the histochemical properties of these granules will be reported