Comment by kjkjadksj
Well outside of breast and ovarian cancer for obvious reasons, most mouse models tend to be male to eliminate the variable of the hormone cycle. But if some effect is actually influenced by that cycle you just ensured you will never find it. I’m also not sure how similar the mouse hormone cycle is to humans.
Also, we're now finding males have a hormonal cycle, but it's less obvious or predictable than females' so those variables have probably been in there all along, just unknown.