Table 2

Different aspects of sex differentiation in marsupials


Y chromosome (testes)
No Y chromosome (absence of testes)

One X chromosome (scrotum)
XY
XO

Male animals with scrotum and testes
Animals without testes and an empty scrotum instead of a pouch
Two X chromosomes (pouch and mammary glands)
XXY
XX

Animals with testes and a pouch with mammary glands instead of scrotum
Female animals with a pouch and mammary glands

The marsupial Y has the ability to turn the undifferentiated gonads into testes, but other aspects of sex differentiation seem to rely on the number of X chromosomes present. This is how we come across the above combinations in sex chromosome aneuploidies in marsupials.

Manolakou et al. Reproductive Biology and Endocrinology 2006 4:59   doi:10.1186/1477-7827-4-59