Especially in western society, more and more men are suffering from fertility problems. It is believed that these could be related to genetic factors, but also to stress and lack of sexual interactions. Fertility tests often reveal that men have problems with the quality of their sperm. The problems are often related to the senescence of the sperm, that is, the aging of these cells and their reduction in quality with age. This is a topic with a growing interest in science, both because of the mechanisms that produce it, and because of the evolutionary consequences it can have.
Until today, various studies have been published in this regard, however, there is still a lack of evidence of sperm senescence at the intratesticular (within the testes) and postmeiotic (after the meiosis process) level in wild animals. A subject on which scientists from the University of Veterinary Medicine Vienna have focused on their latest research. The team has just published their results in the scientific journal PLOS One.
The study focused on Bufo bufo , generally known as the common toad. Males of this species produce and store all the sperm for the year before the breeding season. The researchers monitored the motility changes of these cells throughout the season and did two experiments:
In the first, they experimentally induced re-hibernation at the beginning of the breeding season. By reducing their metabolic rate, the toads stored sperm with significantly higher motility than those kept in semi-natural conditions before the rutting season. This would mean that re-hibernation would slow down the normal aging rates of the sperm.
In the second, they analyzed sperm motility in the group that was kept in semi-natural conditions with the females. In this case, the males that mated more times ended up with significantly more motile sperm than those that did not mate as often. Therefore, these results could suggest that intratesticular postmeiotic senescence of sperm does not have a genetically fixed rate and can be modulated by mating opportunities.
According to the study’s lead author, Attila Hettyey, for the journal Phys , “We still don’t know how widespread postmeiotic senescence of sperm is in wild animals or man. But if it turns out to be widespread, it will be fascinating to see how it affects reproductive behavior. Females may try to avoid males with damaged sperm, while males may choose particular environments that slow sperm senescence and may attempt to shorten periods of sexual rest by also accepting matings with poor-quality females or discharging aged sperm. “
Â
References:
Hettyey, A., Vági, B., Penn, D. J., Hoi, H., & Wagner, R. H. (2012). Post-Meiotic Intra-Testicular Sperm Senescence in a Wild Vertebrate. PLoS ONE, 7(12), e50820. https://doi.org/10.1371/journal.pone.0050820Â
Staff, S. X. (2012, December 4). Fitness for toad sperm: The secret is to mate frequently. Phys.Org. https://phys.org/news/2012-12-toad-sperm-secret-frequently.html Â
