Apart from these studies on the potential physiological implication of steroids in the normal process of gonadal differentiation in salmonids, a few gene expression experiments were carried out to investigate the effects of steroid treatments on gonadal differentiation in rainbow trout. These experiments showed that both masculinization with androgens, and feminization with estrogens, induce important alterations in the gonadal transcriptomes of the treated animals, compared with untreated control males and females [147–149].