[Demonstration of specific gonadotropin binding sites of chum salmon (Oncorhynchus keta) in membrane preparations of granulosa cells from the ovary of amago salmon (Oncorhynchus rhodurus)].

During late vitellogenesis, radioactive iodine labelled Salmon gonadotropin binds to theca--or granulosa--membrane preparations from amago Salmon ovary. In granulosa, native hormone inhibits iodinated GTH binding, thus indicating a specific binding (70% of total binding). In theca, a lower specific binding is found while non specific binding is higher: contamination by granulosa cells, on one hand, the possible heterogeneity of theca, on the other, could account for these results.