In incredible news, scientists have discovered that women's bodies actually have the ability to filter out undesirable sperm in order to avoid genetic issues and create the healthiest babies possible. Findings suggest that each individual woman's reproductive secretions can affect the sperm's performance.
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This information was revealed in a study conducted by researchers from Finland who activated the sperm of eight male donors with either cervical fluid or follicular fluid (the liquid surrounding immature egg cells) extracted from nine women to determine what effect the mucus or fluid would have on the sperm's motility and other factors in the sperm's success.
Reproduction is a selective process.
The research indicates that egg fertilization is a selective process involving the immunological compatibility of the male and female trying to reproduce. Couples who are more genetically compatible have a higher chance of succesfully reproducing.
The results of the study are eye-opening.
"These findings can have important implications for a deeper understanding of sexual selection and the fertilisation process in humans and other mammals," said University of Eastern Finland's Jukka Kekäläinen, a biologist who authored a paper on the study.
It all works together.
The innate human ability to determine compatible mates via smell and physical attributes can make it even easier for the female's reproductive fluids to filter out incompatible sperm, since theoretically a more compatible mate would have mostly sperm that are genetically well-suited to the female, and less would need to be filtered out.
Genetic compatibility is important.
The Finnish researchers discovered that sperm performs better in genetically compatible couples. Meaning, sperm were more successful in partners with very different "human leukocyte antigen" immune genes, which act in creating proteins that are important to the functioning of the immune system.
This helps create healthy babies.
This helps create healthy babies because the more diverse the genes are, the stronger the offspring's immune capacity will be. Past studies have indicated that individuals may naturally seek out immunologically compatible partners based on scent and facial appearance.
There's an additional protection.
The selectiveness of the female reproductive fluids also serves to ensure that couples do not inadvertently inbreed. Since diverse genetic pairings are more successful, if a couple shares DNA, that sperm is more likely to be filtered out by the cervical mucus and/or the follicular fluid.
Cervical mucus is the first barrier.
Cervical mucus is secreted from a woman's cervix throughout the various stages of her menstrual cycle, being more hospitable to sperm leading up to and during ovulation and less so during the rest of the cycle. It protects sperm as it travels to the egg.
Cervical mucus may also be able to assist sperm.
The findings of the study out of Finland suggest that the cervical mucus may also be more favorable toward sperm that is genetically compatible with the woman, giving it a higher chance of success over less-compatible sperm.
The cervical mucus is crucial to successful reproduction.
"Thus, cervical mucus may simultaneously aid migration of functionally normal sperm and serve as a selective barrier for abnormal and poorly motile sperm cells," said the study authors, suggesting that the mucus plays an even more important role in successful reproduction than previously known.
Analysis was comprehensive.
The scientists involved in the study combined sperm and mucus/fluid from each donor in every possible combination, carefully analyzing the sperm's physiological properties in each environment to determine the effects the mucus and/or fluid would have on the sperm's ability to reach the egg.
Many factors were influenced.
The scientists studied all of the factors involved in sperm performance and discovered that "swimming velocity, hyperactivation, and viability" were all influenced by the specific male-female combinations, with genetically dissimilar combinations being more successful.
The findings were fairly conclusive.
There was a clear correlation between the mucus and/or fluid and the success of the sperm. According to the study, "Indeed, accumulating evidence shows that female-derived reproductive secretions can provide multiple opportunities for gamete-mediated mate choice."
More testing is needed.
As is the case with all scientific research, the scientists involved in the study have indicated that additional testing in mammals should be conducted in order to corroborate their findings, before using their research to make fertility determinations.
This information could be huge for infertility treatment.
Knowing the correlation between genetic compatibility and the female body's ability to filter out unwanted sperm could prove hugely beneficial when it comes to diagnosing and treating infertility, especially since so many cases of infertility are considered unexplained.
The findings offer a "deeper understanding."
"Finally, by showing that sperm performance in cervical mucus is influenced by partners' genetic compatibility, the present findings may promote a deeper understanding of infertility," concluded the Finnish researchers.
