In article <1995Jun16.134129.17490 at galileo.cc.rochester.edu>,
ttha at uhura.cc.rochester.edu (Tom Thatcher) wrote:
>> ...I want to correcxt a
> misconception, though, it that cells do not move to their location,
> as you seem to suggest, rather, location determines fate (mostly).
> A newly divided cell in the embryo's tail doesn't think to itself,
> "I'm a brain cell, better get a move on."
Actually, several crucial developmental steps require require cellular
movement in the developming (animal) embryo. Examples include the role
played by primary mesenchyme in sea urchin gastrulation and, closer to
home, the development of sympathetic and parasympathetic ganglia (as well
as other tissues) from migrating neural crest cells.
In his book _Topobiology_, Gerald Edelman discusses the responses of
migrating cells to components of the extracellular matrix, and the effect
that has on the developmental process.
This book, along with _The Making of a Fly_, might shed some light on some
of the original poster's questions.
Matt Brauer <mjbrauer at mail.utexas.edu>
University of Texas
Department of Zoology