SDS

In genetics, "major sex determinant" is the gene that triggers the process of differentiation of the gonads of the embryo and directs them towards the formation of ovaries or testicles. In salmonids, the sex determination system is known to be type XX for females and XY for males, as in mammals. The SDY gene is specifically expressed in embryonic male gonads in rainbow and brown trout. The SDY gene could then be the major sex determinant in these two species and possibly other salmonids.