Effect of Actinomycin D and Cycloheximide on Gonadotropin‐Induced 17α, 20β‐Dihydroxy‐4‐pregnen‐3‐one Production by Intact Ovarian Follicles and Granulosa Cells of the Amago Salmon, Oncorhynchus rhodurus *

The effect of actinomycin D and cycloheximide on gonadotropin (partially purified chum salmon gonadotropin, SGA)‐induced 17α, 20β‐dihydroxy‐4‐pregnen‐3‐one (17α, 20β‐diOHprog, a maturation‐inducing steroid in amago salmon) production was examined in intact ovarian follicles and granulosa cells of postvitellogenic amago salmon, Oncorhynchus rhodurus. Both actinomycin D and cycloheximide blocked gonadotropin‐induced 17α, 20β‐diOHprog production by intact follicles. In contrast, gonadotropin‐induced 17α‐hydroxyprogesterone production by intact follicles was not abolished by actinomycin D, but was abolished by cycloheximide, suggesting that postvitellogenic amago salmon ovarian follicles already contain the RNAs necessary for the synthesis of 17α‐hydroxyprogesterone.