 Defeminization involves the suppression of the development of female typical morphology (development of the Müllerian ducts into the fallopian tubes, uterus and vagina) and behavioural predispositions.Masculinization involves the production of male typical morphology (development of the Wolffian ducts into male reproductive structures) and behavioural predispositions.Both defeminization and masculinization are required for a mammalian zygote to become a fully reproductively functional male.