A newly-discovered protein in the semen of all mammals - including humans - prompts females to ovulate through a direct effect on the brain.It was previously shown that women can be selective about sperm:
Surprisingly, it's the same molecule that regulates the growth, maintenance, and survival of nerve cells - nerve growth factor (NGF) which is found primarily in nerve cells throughout the body.
The scientists, though, say that large amounts of the protein are produced by the accessory sex glands that contribute seminal fluid to semen.
"To our surprise, it turns out they are the same molecule," says Gregg Adams of the University of Saskatchewan. "Even more surprising is that the effects of NGF in the female were not recognized earlier, since it's so abundant in seminal plasma."
NGF in the semen acts as a hormonal signal, working through the hypothalamus of the female brain and the pituitary gland. This triggers the release of other hormones that signal the ovaries to release an egg or eggs.
A woman's body may be unconsciously selective about sperm, allowing some men's to progress to pregnancy but killing off the chances of less suitable matches, an Australian researcher said Wednesday.A physician site says that Assault rape pregnancies are extremely rare.
University of Adelaide professor Sarah Robertson said her research suggested that sperm contains "signaling molecules" that activate immunity changes in a woman so her body accepts it.
But some apparently healthy sperm failed to activate these changes, leading to the suggestion that the female system can be "choosy" about its biological mate, she said.
Todd Akin got into some trouble for making some related comments, but there are commonly much more ridiculous views. There are feminists who refuse to distinguish different kinds of rape, for ideological reasons. So they hate phrases like “legitimate rape”. They say that stranger rape, violent rape, date rape, and marital rape are all the same. They are the ones with the extreme views. And they say that a women claiming rape should always be believed.