SRY and freemartinism: Previous reports have shown that the proportion of XY cells in karyotypes of freemartins was not related with the degree of masculinization and inhibition of ovary or Müllerian duct development, whereas, currently, the diagnosis of freemartinism includes qualitative and quantitative detection of the SRY gene in the aspect of the effect on fertility of females originating from twin calves of different genders (6).