Steve Harris wrote:
> Somehow I knew you were going to say that.
Likewise :-)
> However, I seem to
> remember that there are techniques of taking ovaries from a cow and
> using a far higher fraction of the oocytes in them to make calves, than
> would normally be released in a lifetime. Thus, the ones subject to
> normal atresia actually seem fine-- they are just wasted. That would
> certainly argue that they are being selected out because of some
> defect.
I don't think so. If there is a competition stage in the determination
of which oocyte gets made available for fertilisation (which is what I
gather from the article I just mentioned, Gynecol Endocrinol 7:285, but
I'd welcome any references to a contrary view), then all it implies is
that the process errs on the side of caution, by initiating development
of enough oocytes that far more than one is likely to be competent. Not
much different from the male side, in other words. I'd be interested
to know just what fraction made it to calves though -- if you recall the
reference I'd be grateful, as the only work I could find looked at the
growth competence of the oocyte but didn't perform any fertilisation.
Aubrey de Grey
