Category sperm

Your egg may not agree with your mating partner

By ingender selection, research, sperm

Your egg might prefer some men’s sperm over others.

Microscopic mate choice

“Follicular fluid from one female was better at attracting sperm from one male, while follicular fluid from another female was better at attracting sperm from a different male,” said Professor Fitzpatrick.

“This shows that interactions between human eggs and sperm depend on the specific identity of the women and men involved.” 

The egg might have its own preference in type of sperm and it is exercised by follicular fluid. The egg might attract more sperm from a certain male and not always the partner. So is the egg the decision maker in fertilization or the sperm? We have always thought that the sperm swims towards the egg and therefore is the one choosing the egg. The egg basically is a passive participant, waiting for the sperm. However recent research shows there may more than meet the eye.

Perhaps it makes sense since the egg has to risk it all, get one sperm, implant and become a human, whereas the sperm are in millions, anyone of them wins, the male wins. To find out more about mating and reproductive behaviors and opportunities, read up more on Professor John Fitzpatrick’s research on reproductive behaviors, opportunities and trade offs (https://www.su.se/english/profiles/jfrit-1.253654).

“The idea that eggs are choosing sperm is really novel in human fertility,” said Professor Daniel Brison, the Scientific Director of the Department of Reproductive Medicine at Saint Marys’ Hospital, which is part of MFT, and the senior author of this study. 

The University of Manchester Honorary Professor added: “Research on the way eggs and sperm interact will advance fertility treatments and may eventually help us understand some of the currently ‘unexplained’ causes of infertility in couples.”

“I’d like to thank every person who took part in this study and contributed to these findings, which may benefit couples struggling with infertility in future.”

The article Chemical signals from eggs facilitate cryptic female choice in humans is published in the scientific journal Proceedings of the Royal Society B.

https://royalsocietypublishing.org/doi/10.1098/rspb.2020.0805

Research was supported by the Manchester University NHS Foundation Trust, the University of Manchester, the National Institutes of Health Research, a Knut and Alice Wallenberg Academy Fellowship, and a Wenner Gren Fellowship.

Source: https://www.su.se/english/research/human-eggs-prefer-some-men-s-sperm-over-others-research-shows-1.503532#:~:text=students%20and%20staff-,Human%20eggs%20prefer%20some%20men’s%20sperm%20over%20others%2C%20research%20shows,signals%20to%20%E2%80%9Cchoose%E2%80%9D%20sperm.

Male Social Dominance and ejaculate quality

By inresearch, sperm Tag ,

According to research published in Behavioral Ecology, February 2021, quality of the ‘creame’ and social dominance is linked.

Research shows that higher social status not only increase a male’s access to potential mates but also production of high quality ejaculation.

The research shows, social status influence ejaculate traits, regardless whether female are present.

Dominant male produce faster swimming and viable sperm.

Higher social status is expected to result in fitness benefits as it secures access to potential mates. In promiscuous species, male reproductive success is also determined by an individual’s ability to compete for fertilization after mating by producing high-quality ejaculates. However, the complex relationship between a male’s investment in social status and ejaculates remains unclear. Here, we examine how male social status influences ejaculate quality under a range of social contexts in the pygmy halfbeak Dermogenys collettei, a small, group-living, internally fertilizing freshwater fish. We show that male social status influences ejaculate traits, both in the presence and absence of females. Dominant males produced faster swimming and more viable sperm, two key determinants of ejaculate quality, but only under conditions with frequent male–male behavioral interactions. When male–male interactions were experimentally reduced through the addition of a refuge, differences in ejaculate traits of dominant and subordinate males disappeared. Furthermore, dominant males were in a better condition, growing faster, and possessing larger livers, highlighting a possible condition dependence of competitive traits. Contrary to expectations, female presence or absence did not affect sperm swimming speed or testes mass. Together, these results suggest a positive relationship between social status and ejaculate quality in halfbeaks and highlight that the strength of behavioral interactions between males is a key driver of social-status-dependent differences in ejaculate traits.

For more information, find research paper from

https://academic.oup.com/beheco/article/32/1/168/6008100?login=true

Male-male behavioral interactions drive social-dominance-mediated differences in ejaculate traits.

Charel Reuland, Brett M Culbert, Erika Fernlund Isaksson, Ariel F Kahrl, Alessandro Devigili, John L FitzpatrickBehavioral Ecology, Volume 32, Issue 1, January/February 2021, Pages 168–177, https://doi.org/10.1093/beheco/araa118