Feature

As Told By the Egg

The story of fertilization, from the female point of view

Whether the chicken or the egg came first doesn’t occupy biologist Luca Jovine’s thoughts too much. Animals have been laying eggs for millions of years, after all. Over time, evolution has reshaped both the eggs and the creatures hatched from them.

Studies are suggesting that sperm aren’t completely in control when it comes to fertilization. ~~ David M. Phillips/Photo Researchers, Inc.

INTIMATE ENCOUNTER | In mammals, millions of sperm race through the female reproductive tract vying to be the first to access the egg. But the sperm have to get through a protective membrane called the zona pellucida.

Source: K.G. Claw and W. Awanson/Ann. Rev. Genomics Hum. Genet. 2012 ~~ E. Feliciano