Generation of the four core genotype. The Sry gene was spontaneously deleted from the Y chromosome (Y-) and transferred to an autosome resulting in the XY-
Sry male mouse. Breeding XX females with XY-
Sry males produces the four core genotype: XY- and XX females and XY-
Sry and XXSry males. We refer to XX and XY- as XX and XY-Females and XXSry and XY-
Sry as XX- and XY-Males throughout the text.