https://phys.org/news/2019-01-cilia-unexpected-rhythm-male-reproductive.html

"Motile cilia are eyelashlike extensions of specific epithelial cells and have a beat that moves fluid over a surface," said Rex Hess, a University of Illinois professor emeritus of comparative biosciences and a major collaborator on the study led by Dr. Wei Yan, a foundation professor of physiology and cell biology at the University of Nevada, Reno School of Medicine.

"For more than 150 years, most papers and books on the subject stated that motile cilia of the efferent ductules move sperm cells in one direction, like they do in the female fallopian tubes," Hess said. "But we found that the cilia in this organ beat in an unusual manner that stirs and agitates the luminal fluid and sperm.