The difference between men and women is whether our cells have either XX = female, or XY = male, or that’s what we’ve long been taught. But Last wek some new reasearch on white mice seems to undermine this. Without a Y the cells were said to be the default sex, ie female. This is from Steve Connor in the i newspaper:
“a team led by Professor Monika Ward of the university of Hawaii has shown that it is still possible for a mouse without any Y chromosome to develop into a fertile male. The proviso is that it has 2 other genes functioning – the testes-determinant factor Sry, and he spermagonial proliferation factor (Eif2s3y). In a study published in Science, they showed”no Y” males were able to produce viable sperm,which when used to produce IVF embryos, gave rise to fertile, healthy offspring. Although te sons and grandsons also lacked a Y, they were capable of producing further generations without IVF.
“Most of the mouse Y chromosome genes are necessary for development of mature sperm and normal fertilisation, both in mice and in humans. However, when it comes to assisted reproduction, we have now shown that in the muse the Y chromosome contribution is not necessary,” Professor Ward said.
The scientists were able to exploit similar genes for Sry and Eif2s3y on other chromosomes to take over the functions lost by the Y chromosome. They believe this is an important discovery as it may ultimately help infertile men who want children. “It suggests that there are back-up strategies within genomes, which are normally silent but are capable of taking over under certain circumstances.”