If you don’t remember your reproduction lessons from yesteryear, male sperm face a perilous journey to beat the competition and fertilize an egg after intercourse. Scientists have now discovered that some of those swimmers receive an unexpected helping hand at the end of the journey, though.
According to researchers in the UK, a “motherhood” protein on the outside of the egg cell effectively reaches out to grasp the winner and draws it inside. Apparently the “reach” has never been seen or studied before, and scientists think it could hold the key to reproductive issues and infertility.
Researchers named the protein “Maia” after the Greek goddess of motherhood.
Professor Allan Pacey, of the University of Sheffield and co-author of the study, said: “This discovery of the Maia protein is a major step forward in how we understand the process of human fertilization.”
Men will release between 40 million and 150 million sperm during ejaculation, depending on their health; yet only a few hundred possess the strength to swim to the egg. Although the uterus muscles will aid in the flow, the female immune system also purposely tries to eliminate all unworthy candidates with a host of obstacles.
The relationship between egg, sperm, and infertility is now better understood thanks to the discovery of the Maia protein
What’s always confounded researchers, though, is why some sperm still struggle to enter the egg’s cytoplasm and fertilize even after the arduous journey. As it turns out, it may not have been the sperm’s fault — the egg looking for fertilization may not have had the correct protein attached.
To study which egg proteins were helping or hindering the sperm, scientists created artificial eggs from beads, and attached different pieces of peptide proteins to their surface to see if any obviously instigated a bonding. After introducing sperm to the fake eggs and incubating them, researchers found that only those with parts of the Maia protein successfully entered.
Professor Harry Moore, lead investigator of the study, said: “The ingenious artificial fertilization technique, which enabled us to identify the Maia protein, will not only allow scientists to better understand the mechanisms of human fertility, but will pave the way for novel ways to treat infertility and revolutionize the design of future contraceptives.
“Infertility is unexplained in more than half of those who struggle to conceive naturally.”
Next up is to study the Maia gene more thoroughly, in order to see how it reacts to different sperm. If there turns out to be a connection between the protein and specific traits of specific sperm, fertility experts could come up with workarounds to help couples struggling to get pregnant.