A gene has been discovered that may play an important role in the development of sperm.
A report published in the journal Nature reveals that mice bred without the Jhdma2a gene had unusually small testes.
They produced only tiny amounts of sperm and the few sperm that were generated had abnormal heads and dysfunctional tails, rendering the mice infertile.
The researchers, from the University of North Carolina, suggest that the gene may therefore be vital for sperm production.
Lead researcher Dr Yi Zhang, professor of biochemistry and biophysics at the university's School of Medicine, commented: "Defects in this gene could be the cause of some cases of male infertility.
"Because this gene has a very specific effect on the development of functional sperm, it holds great potential as a target for new infertility treatments that are unlikely to disrupt other functions within the body."
Dr Allan Pacey, senior andrology lecturer at the University of Sheffield, told the BBC:
"It would be very useful to translate this research into human males and see if it can explain why some men simply don't produce healthy sperm and are therefore sub-fertile."