Jim Mossman, lead author of the study and a postdoctoral scholar at Brown University, commented:
"Our study reveals that men who produce higher concentrations of competent swimming sperm also demonstrate less variation in the size and shape of those sperm. It suggests that in some cases, tests are working more optimally to produce high numbers of consistently manufactured sperm, and vice versa."
Mossman and his team measured the flagella, middles, and heads of 30 sperm per person from 103 men who were chosen at random out of 500 individuals who had previously been enlisted in another substantial fertility study.
The team also measured other sperm factors that the WHO (World Health Organization) claims are important fertility indicators, such as concentration and motility.
A study published in August of this year indicated that males who ate a 75g pack of walnuts each day had improved motility, structure, and vitality of their sperm.
"The WHO suggests that measurements should be made on multiple components of sperm, but generally it's only the sperm head that is considered, said Mossman. No one's ever looked at this before across sperm components. What we show is that measurements on other sperm parts, such as the flagellum that propels the sperm, can provide additional information about the quality and consistency of sperm manufacture."
The study revealed two significant findings. The researchers found that men who had higher average flagellum length, total length of sperm, and flagellum-to-head length ratios had higher numbers of sperm capable of movability. Also, they discovered that men's concentration of sperm that could swim well was lowered when the inconsistency of length in the sperm was higher.
Mossman explained, "The finding could give clinicians new insight into the diagnosis and treatment of male fertility problems, which accounts for up to 50 percent of the cases where couples struggle to conceive."
The findings show that inconsistency in the length of a male's sperm could indicate problems with spermatogenesis, or producing sperm, which is then associated with a lower number of strong sperm swimmers. "This could be an indirect marker of testis function," said Mossman. He continued saying that they did not find anything during their trial which describes how spermatogenesis problems form which would explain inconsistency in length of sperm or low motile sperm concentrations.
"There are so many factors that govern sperm productions, including environmental factors, genetic factors, and their interaction. As an andrologist and evolutionary biologist, I am very interested in what causes this variations and how that affects the phenotype of the sperm and its fertility potential."