Comparative fine structure of the axial skeleton inside the regenerated tail of some lizard species and the tuatara (Sphenodon punctatus).

The regenerated tail of the New Zealand gecko Hoplodactylus maculatus is equipped with an elastic cartilaginous tube as skeletal axis. Other lizard species and Sphenodon punctatus possess variably developed hyaline cartilaginous tubes. Moreover, H. maculatus enhances the functional performance of its tail by long elastic fibres, which are arranged all around the central regenerated spinal cord. The different characteristics of the regenerated skeleton could be related to the different environments that the species studied occupy in nature.