A MORPHOMETRIC ANALYSIS OF THE SUBCELLULAR-DISTRIBUTION LH-BETA AND FSH-BETA IN SECRETORY GRANULES IN THE PITUITARY GONADOTROPHS OF THE FROG (RANA-JAPONICA)

Immunohistochemical localization of lutropin beta (LH beta) and follit ropin beta (FSH beta) in the pituitary gland of the frog Rana japonica was studied by the peroxidase-anti-peroxidase method and the two-face , double-labeling method with different-sized gold particles at the li ght- and electron-microscopic levels, respectively, using monoclonal a ntibodies against bullfrog LH beta and FSH beta. Light-microscopic imm unohistochemistry indicated that approximately 66.0% of all the gonado trophs in the pituitary contained both LH beta and FSH beta, whereas 3 3.4% of gonadotrophs contained only LH beta, and 0.6% contained only F SH beta. The staining intensity of LH beta and FSH beta varied from ce ll to cell. The gonadotrophs were classified into four types (Types I- IV) in terms of their ultrastructural and immunolabeling characteristi cs. Moreover, several secretory granule types were recognized accordin g to differences in their shape and electron density. In all the cell types, both LH beta and FSH beta were often seen in the same secretory granules, but the proportion of granules bearing both hormones ranged from 5.5% in Type I to 32.7% in Type IV, Most secretory granules in T ypes I and II were immunolabeled with LH beta alone, whereas a small n umber of granules were immunolabeled with FSH beta alone. More immunol abeled FSH beta granules were present in Types III and IV than in Type s I and II.