A University of Nevada researcher has revealed a new source of male infertility. According to School of Medicine Professor, Wei Yan, M.D., new research as uncovered efferent duct obstructions as a new cause of male infertility, correcting a long-held concept regarding sperm transport.
“Men produce millions of sperm daily,” he said. “When sperm are produced inside the testis, they cannot swim. They have to be flushed out by testicular fluid, which carries them further to the tiny efferent ducts that are smaller than the sperm themselves.”
There was a perception that motile cilia, or eyelash-like extensions of specific epithelial cells, push sperm forward in one direction through efferent ducts.
“Our study demonstrates that this is not the case,” Yan said.
It turns out that motile cilia in the male reproductive tract beat with continual changes in direction.
“In this way, cilia function to stir things up instead of transport. If cilia stop beating, sperm will accumulate into clumps that block the efferent ducts. As a result, fluids build up, causing testicular damage and male infertility.”
The research poses a question of how millions of immotile sperm can pass through such narrow channels successfully, without clogging.
When the fluid back pressure is relieved through a simple surgical procedure, fertility can improve. The findings could lead to new methods in treating male infertility.
“Our research discovered not only a new cause of male infertility but also a potential new treatment for male infertility caused by efferent duct obstructions,” Yan said.
Among one-third of couples who have fertility problems, men are often the cause of infertility.