The older the sperm, the healthier and longer-lived the offspring would be. Weird? We explain to you.
About 100 million sperm are present in one milliliter of semen. Their shape may vary. Swedish and English researchers have shown that the age of the spermatozoa influences their quality: the “older” they are, the healthier their offspring will be and themselves endowed with significant longevity. The findings of this study, conducted by the universities of Uppsala in Sweden and East Anglia in the UK, have been published in the scientific journal Evolution Letters.
Scientists have used zebrafish for their research. 70 to 85% of the genes of this tropical species have an equivalent in humans. Several characteristics of this animal have allowed it to become a very important model organism in research. And for this study, the researchers were interested in its reproductive system.
Healthier fish with greater longevity
The scientists first collected male and female gametes, then they divided the sperm into two separate groups based on their age. The first group was directly used for in-vitro fertilization, the second was used after 25 seconds. For two years, the researchers followed the evolution of the offspring resulting from this experiment.
“Until now, everyone assumed that knowing which sperm fertilized the egg was not so important, as long as it was able to fertilize it,” explains Simone Immler, one of the authors of this study. But the results of their experiment prove the opposite: the fish from the “older” spermatozoa were generally healthier and more fertile than the others, even though they came from the same parent. According to the researchers, these results could make it possible to improve in-vitro fertilization techniques. For now, they are continuing their research to better understand which genes are involved in this process.
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