Human and mouse male reproductive cells find the egg by migrating upstream
Mammalian sperm just don’t go with the flow.
The little swimmers use head-on currents to guide themselves up fallopian tubes toward an egg, a new study suggests. Sex triggers fluids to spurt from the fallopian tubes, where tiny bristles called cilia sweep the fluid from the ovaries to the uterus. The moving fluid hands sperm a map to their target, researchers report online February 28 in Current Biology.
“I like this paper because it stirs up the field,” says Susan Suarez, a reproductive biologist at Cornell University in Ithaca, N.Y., who specializes in sperm movement. Scientists had proposed two other ways sperm might find eggs: by sniffing out chemicals