Page URL:

Sperm change swimming patterns to find egg

15 November 2021
Appeared in BioNews 1121

Research has shed light on how the chemical environment of the fallopian tubes can influence how mammalian sperm swim towards the egg

Researchers at Cornell University in Ithaca, New York, monitored the swimming activity of bovine sperm when exposed to biochemical cues from the environment. Sperm generally performed a symmetrical pattern of swimming with their flagellum (tail) and travelled in a straight line. However, exposure to agents which increased intracellular calcium, including caffeine, induced 'hyperactivation' – a state associated with asymmetrical beating of the flagellum and a circular swimming pattern.

'We think that hyperactivation modulates sperm's swimming behaviour as it ascends towards the fertilisation site… and as sperm responds to the biochemical factors present in the environment' said first author Meisam Zaferani, a graduate student in the lab of Professor Alireza Abbaspourrad. Therefore, this shift in motility, which is known to occur in the fallopian tube enables the sperm to search the area for the egg, encouraging successful fertilisation

In the study, the team used custom-made microfluidic chambers to observe sperm motility in different chemical environments. Sperm had a tendency to hug the chamber walls as they swam in a straight line using their flagellum in a symmetrical fashion, similar to how they are understood to swim in the female reproductive tract. In the presence of an influx of calcium, the flagellum was shown to switch to asymmetrical beating causing the sperm to swim in a circular swimming pattern. Authors argued this would prevent the sperm from venturing into intrauterine 'dead ends'. 

Our understanding of mechanisms governing sperm motility has advanced over recent years (see BioNews 1078 and 1102) now known to include factors such as temperature gradients, fluid flow and uterine wall architecture. However, it remains to be seen what governs this intracellular rise in calcium levels in living organisms including humans, as this new evidence is solely from an artificial in vitro context.

Nonetheless, as senior author Professor Abbaspourrad said, 'By understanding what determines the navigational mechanism… we may be able to use those cues to treat couples with infertility issues and select the best strategy for in vitro fertilisation'. 

The study is published in the Proceedings of the National Academy of Sciences.

Mammalian sperm hyperactivation regulates navigation via physical boundaries and promotes pseudo-chemotaxis
Proceedings of the National Academy of Sciences of the United States of America |  2 November 2021
Sperm switch swimming patterns to locate egg
Cornell Chronicle |  1 November 2021
5 July 2021 - by Dr Charlotte Douglas 
An essential component of how sperm move has been discovered, opening up new avenues for the understanding and treatment of male infertility...
11 January 2021 - by Daniel Jacobson 
A molecular mechanism enabling correct sperm motility has been uncovered, shedding light on a key cause of male infertility...
14 December 2020 - by Anna Wernick 
Did you know that all successful sperm must be sleek, speedy and streamlined?...
10 August 2020 - by Bernie Owusu-Yaw 
Research using high-precision 3D microscopy has overturned 350-year-old observations about how sperm swim...
18 February 2019 - by Jakki Magowan 
Slower sperm are beaten by stronger and faster sperm when competing to fertilise an egg due to restrictive bottlenecks in the female reproductive tract...
to add a Comment.

By posting a comment you agree to abide by the BioNews terms and conditions

Syndicate this story - click here to enquire about using this story.