[extropy-chat] Ontogeny recapitulates phylogeny
jrd1415 at yahoo.com
Tue May 24 20:38:31 UTC 2005
Bacteria evolved biomolecular motors and the cilia to
go with them. These very early
ontogenic/phylogenic steps are still with us and as
crucial as ever.
Humans and other animals may appear to be symmetrical
on the outside, but symmetry is only skin deep. Many
body organs, such as the stomach, the heart and the
liver, are tipped to the right or left side. So how
does the developing embryo distinguish left from
right? Salk scientists have now discovered that the
foundations for the basic left-right body plan are
laid by a microscopic 'pump' on the outer surface of
the embryo's underside that wafts chemical messengers
over to the left side of the body. This sets up a
chemical concentration gradient that tells stem cells
how and where to develop. The remarkable findings,
including movie footage of the 'pump,' are published
in the May 20th edition of the journal Cell.
Best, Jeff Davis
"Everything's hard till you know how to do it."
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