The testis-determining gene Sry is located on the short arm of the mouse Y 
chromosome in a region known to have undergone duplications and rearrangements 
in comparison with the equivalent portion of the human Y chromosome. Detailed 
analysis of the Sry genomic locus reveals a further difference in that the mouse 
Sry open reading frame lies within 2.8 kilobases of unique sequence at the 
center of a large inverted repeat. This repeat, which is found in both Mus 
musculus musculus and Mus musculus domesticus Y chromosomes, is not present at 
the human SRY locus. Recombination involving the repeat region may have led to 
an 11-kilobase deletion, precisely excising Sry in a line of XY female mice.