Abstract Chicken(Gallus gallus) is an important model organism and agricultural animal. Its sexuality is an important developmental trait in biological aspect and an economic character in poultry industry. However, the molecular mechanisms of sex determination and differentiation remain elusive in chicken. Despite the sex phenotype is determined by genes in a dichotomous ZZ/ZW sex chromosome, formation and differentiation of gonad and body gender is largely influenced by environmental factors, for instance hormone of estrogen. Regarding to the sexuality of chicken, there are two hypotheses that are referred as W-linked ovary determinant and Z dosage for testis determination, both of which are lack of convincing evidence. In this review, we have not only summarized the previous studies but also presented some new data on the epigenetics and cell autonomy in chicken sex determination and differentiation.
