David H. Freedman writes in New Theory on How The Aggressive Egg Attracts Sperm:

As they mill around, the egg selects one and reels it in, pinning it down in spite of its efforts to escape. It’s no contest, really. The gigantic, hardy egg yanks this tiny sperm inside, distills out the chromosomes, and sets out to become an embryo.

Or would you have put it differently? Until very recently, so would most biologists. For decades they’ve been portraying sperm as intrepid warriors battling their way to an aging, passive egg that can do little but await the sturdy victor’s final, bold plunge. But the first description is closer to the truth, insists Emily Martin, a 47-year-old researcher at Johns Hopkins who has spent the past seven years examining the metaphors used to describe fertilization.

Is Emily Martin correct and the egg is much more active than popular culture assumes?

  • Is this a theory or a factual statement? The title of your example says "theory", which would make this off topic here.
    – Sklivvz
    Oct 22, 2015 at 13:10
  • @Sklivvz: It's clearly a claim about something that may or may not happen in real life. The linked article suggests that it may be supported by empirical evidence. The question seems fine to me. Oct 22, 2015 at 13:35
  • I'm having trouble with this question as well. I can't see any facts that are in dispute. The issue may be an important, but it isn't two models that predict different facts that can be empirically tested, but which of two descriptions is less likely to trigger biased thinking.
    – Oddthinking
    Oct 22, 2015 at 13:47
  • I don't think the word theory as used in science means that something has no factual basis. Emily characterises the interaction between the eggs pinning down the sperm and yanking it in. The standard view is that the egg is passive. I that there a factual difference between those two views. Do you think there no factual difference?
    – Christian
    Oct 22, 2015 at 15:45
  • 5
    I'm not sure anthropomorphizing cells would be scientifically accurate either way.
    – user5341
    Oct 22, 2015 at 16:14

1 Answer 1


Research referred by Emily Martin in her 1991 paper 'The Egg and the Sperm: How Science Has Constructed a Romance Based on Stereotypical Male Female Roles' show that the sperm and egg are mutually active partners who do interact on more mutual terms. There is a take 2 for the egg and the sperm tale coming up with Richard Cone according to her CV present here.

  1. Research by Gerald Schatten and Helen Schatten show that the "egg is not merely a large, yolk-filled sphere into which the sperm burrows to endow new life.

The Schatten lab has the egg's nucleus "interrupt" the sperm's dive with a "sudden and swift" rush by which she "clasps the sperm and guides its nucleus to the center.

  1. Biophysicists at Johns Hopkins concluded that the sperm and egg stick together because of adhesive molecules on their surfaces.

In the Johns Hopkins lab's revised model, the egg ends up as the female aggressor who "captures and tethers" the sperm with her sticky zona, rather like a spider lying in wait in her web.

  1. Paul M. Wassarman mentions that "the driving force for engulfment of a fused sperm comes from a region of cytoplasm just beneath an egg's plasma membrane."

Wassarman's description of the surface of the egg "covered with thousands of plasma membrane bound projections, called microvilli" that reach out and clasp the sperm adds to the spiderlike imagery.

  1. Cybernetic model on the interaction between egg and the sperm.

J. F. Hartman's research in reproductive biology demonstrated fifteen years ago that if an egg is killed by being pricked with a needle, live sperm cannot get through the zona.

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