Female biology screens for the best sperm: Study
A new study has revealed that the female reproductive system is 'choosy' when it comes to inferior quality sperm and rejects the 'advances' of spermatozoa that are not good enough to create a pregnancy.
University of Adelaide Professor Sarah Robertson, the lead researcher explained, "We actually think that some women are more choosy than others, if you like...Part of this whole process is it's a way for the female body to evaluate whether the time is right and whether this particular partner is the right one to conceive a child with...Some women have higher thresholds to responding to this signalling pathway. It might be that with one partner they're having more trouble than they might with another partner." She went on to say, "What we understand is that there is a partner-specific component to this. Some combinations of men and women might not be compatible and it's possible that the immune systems of some women aren't responding correctly to their partner's triggering molecules...The fault can be in the male or female part of the communication pathway." She called this complex interaction a "two way dance" between partners.
What happens after sex?
Professor Robertson plans to study this signalling phenomenon in detail and in real life situations and says further tests and investigations may reveal more details. "What we're trying to do with our current research is to look into what happens after people have sex to be able to investigate in the real-life situation whether the seminal fluid is signalling between the male and female partner," she said. At present the findings are based on mice and pigs but she believes that the theory holds true for human females too.
She went on to explain the study, "We've discovered that there are signalling molecules in the seminal fluid, so that after coitus when that fluid travels from the male to the female reproductive tissues it activates gene expression changes and also changes in the female immune system that increase the likelihood of a pregnancy occurring...At the moment we've done lots of work on mice and pigs and we've done a little bit of work with human cells and we've found if we put seminal fluid on cells in vitro that we get the same kind of changes in human cells...We also have a little bit of preliminary work from people showing or suggesting that the same things are going to occur in real life, in vivo situations."
Men don't need to be so choosy; women do
According to Professor Robertson, this changes the perspective of 'opportunities' of getting pregnant for males and females completely. "If you think about it the female only has a limited number of opportunities in her life to become pregnant... where a male has unlimited opportunities, so he doesn't need to be quite so choosy...
It's really important for the female body to make sure that if she's going to become pregnant that the time is right and conditions are appropriate for making that investment in reproductive energy...We think it's a way biology has developed to avoid becoming pregnant with genetically damaged male sperm...
Alternatively, it might be a way for the female body to avoid getting pregnant when resources are bad; for example in the conditions of famine or high stress, or other kinds of situations where it wouldn't be a good time for a woman to fall pregnant."