An important point: I have personally observed particular members of the old male guard in cell biology reliably applying much harsher standards to their female colleagues and students than to their male colleagues unreasonably and repetitively. (EDIT: it sure isn't everyone or even a plurality but it sure is a visible pattern)

This leads to women (being over half my field at the PhD level) leaving their associations with these men and staying the heck away, as anyone would when being criticized and judged unfairly.

Thankfully I can say this is becoming much less common as the field turns over, and there are more options and sane colleagues available now such that female scientists need to put up with unreasonable behavior or leave all together much less frequently these days.