Abstract
Administration of pregnant mare serum gonadotropin (SG) produced an increase in the uptake of S35 by mouse ovary but had no effect on the uptake of the p32. The P32 was concentrated in the follicular granulosa and the S35 in the follicular fluid. Radiophosphate also appeared to accumulate in the corpora lutea. Accumulation of S35 appears to be highly specific for gonadotropic hormones possessing follicle-stimulating properties.