Separation and maturation of gonadotrophs from 2A8 clonal cells in vitro.

2A8 clonal cells derived from the epithlium of Rathke's pouch of fetal rats were cultured in growth medium supplemented with fresh rat serum, median-eminence extract and 1-thyroxine. Then, in order to isolate gonadotrophs, cyanogen bromide-activated Sepharose whichwas conjugated with LHRH (LHRH-Sepharose) was added to the culture medium. Fourteen days after incubation of 2A8 cells with LHRH-Sepharose, agranular and granular cells were rapidly bound to LHRH-Sepharose when fresh serum had previously been added in the medium. The cytoplasm of granular cells that were bound to LHRH-Sepharose contained spherical secretory granules (200-250 nm in diameter). These cells were similar in morphology to the FSH and LH gonadotrophs described by Kurosumi (1968). Moreover, many of them appeared as hypertrophied cells that resembled "castration" cells. These results demonstrate that LHRH conjugated to Sepharose can be used to separate gonadotrophs from other 2A8 cells, and it is suggested that the hypertrophy of some cells might be due to persistent stimulation by LHRH which is likely bound to receptors on the cell membrane.