pcsmith at alpha2.csd.uwm.edu (Paul Curtis Smith) wrote:
>Judy E. Stern (Judy.E.Stern at DARTMOUTH.EDU) wrote:
>: In response to the recent correspondence on sperm-egg interaction, you may want
>: to make note of the following description which appeared in Discover Magazine
>: in 1992.
The discussion so far has focused on mammalian sperm-egg interactions.
Mammals represent a very small fraction of all sperm-producing
organisms. In Drosophila, sperm motility does not permit them to
progress forwards, but somehow they get into the storage organs; then
the female releases one at a time as an egg goes by. In Hymenoptera
(wasps, ants, bees, etc.) females only release sperm from their
storage organs when they want to make a daughter; sons result from
infertile eggs. Some very important work on sperm-egg chemical
recognition is being conducted with sea urchins, which are broadcast
spawners (sperm and eggs find each other in the water column). In
plants, there is extensive abortion of fertilized tissue; the degree
to which such abortion is selective is a topic of much study now.
In none of these non-mammalian taxa would the image of sperm fighting
for an egg be anything but a joke (some people do speculate that
pollen tubes "race" to the egg but selective abortion may be as
important as the outcome of the race in determining the identity of
the next generation).
I agree with several commentators that Cameron may be dealing with
a difficulty in textbooks rather than a difficulty in research.
Clearly the textbook authors are mammal-centric as well as all
else. Would a comparative physiology textbook use phrases like the
ones she quoted? I hope not.