Well, that's sort of what I mean....I would just say that whatever you think happens to genital flesh, it's likely that the same thing happens to fetus flesh, ie the fetus tissue morphs along with the uterus into....um....whatever it's morphing into.

Simplest seems to be fetus=genitals for the purpose of this. But really, I have no idea what I'm talking about and just talking because, well, it's kinda fun.