The sex in chicken is determined by the inheritance of sex chromosomes (male ZZ and female ZW). It is well known that the gonads develop into ovaries or testes during embryonic life, this process must be triggered by sex-determining genes, which are the Z-linked DMRT1 and cHEMGN genes. On the other hand, the sex determination in reptiles depends on environmental temperature, which is called TSD (temperature-dependent sex-determination system). Based on the TSD, chicken, which are genetically closed to reptiles, maybe follow same manner in sex determination. In this basic study, the purpose is to find the difference between genotype of molecular sex determination and phenotype by anatomical observation to sex organs of developmental eggs at 10th day embryo.
Total seven hundred eggs of commercial chicken, White Leghorn, were incubated under 37.9 oC, and then five conditions of temperature, 32.9, 35.9, 36.9, 37.9 and 38.9 oC in an incubator with a constant humidity were prepared.
The sex ratio of male and female was 1.08 : 1.00. In five conditions of environmental temperature, several individuals with difference between the genotype and the phenotype were found, especially at 32.9 oC, three in 100 chicks had the difference. Therefore it is suggested that chicken probably depend on TSD in embryo development. Our result is important to understand how temperature may affect morphological, physiological, behavioral as well as genetical sex determination in further studies.