The present review covers a very neglected field in regeneration
studies, namely, tissue and organ regeneration in reptiles, especially
represented by the lizard model of regeneration. The term "regeneration"
is intended here as "the ability of an adult organism to recover damaged
or completely lost body parts or organs." The process of recovery is
further termed "restitutive regeneration" when the lost part is reformed
and capable of performing the complete or partial physiological activity
performed by the original, lost body part. Lizards represent the only
amniotes that at the same time show successful organ regeneration, in
the tail, and organ failure, in the limb (Marcucci 1930a, b; Simpson
1961, 1970, 1983). This condition offers a unique opportunity to study
at the same time mechanisms that in different regions of the same animal
control the success or failure of regeneration. The lizard model is
usually neglected in the literature despite the fact that the lizard is
an amniote with a basic histological structure similar to that of
mammals, and it is therefore a better model than the salamander (an a-
mniote) model to investigate regeneration issues.