Last updated on March 14, 2014 at 16:44 EDT  Mechanisms Behind
Trunk To Tail Transition In Vertebrates Revealed In New Study
June 11, 2013 Imaeg Caption: During trunk to tail transition in
a normal embryo (A), Isl1 is activated exclusively in the
progenitors that produce the organs in the trunk. They now
cannot make organs anymore and make legs as their final destiny.
If there is a failure in the regulation of Isl1 activation and
it is extended to the progenitors that form the spine (B), they
also receive the stop signal and disappear without a trace. Now
these embryos cannot make more vertebrae and malformations are
produced, which look similar to those observed in the patients
for the spinal segmental disgenesis. Credit: Credits: Moisés
Mallo, IGC.  Instituto Gulbenkian de Ciencia  One of the most
remarkable anatomical differences among vertebrate bodies is the
relative size of their neck, trunk and tail. This can be
illustrated by comparing the bodies of a typical snake and of a
long tailed lizard. They a