Sex Determining Mechanism Chromosomal mechanisms(XY &o Two sex chromosomes of different sizes, X is larger . Females are XX males are Xr g Males determine the sex of the offspring Y chromosome TDF: testis-determining factor & SRY: sex-determining region of Y chromosomeSex Determining Mechanism Chromosomal mechanisms (XY) Y chromosome ❖ Two sex chromosomes of different sizes, X is larger ❖ TDF：testis-determining factor ❖ SRY：sex-determining region of Y chromosome ❖ Females are XX, males are XY ❖ Males determine the sex of the offspring