Tail regeneration in the leopard gecko, Eublepharis macularius: Gross anatomy, histology and patterning

Regeneration is a dramatic phenomenon that results in the replacement of lost or damaged structures. Among amniotes the most striking example is tail regeneration in lizards. The objective of this study was to investigate the anatomy and histology of tail regeneration in the representative lizard Eublepharis macularius. Tail structure and tissue composition were examined at multiple time points throughout regeneration. Seven stages of regeneration were identified based on conserved changes in external morphology. Following tail loss there is a period of wound healing followed by blastema formation, angiogenesis and nervous system re-development. Skeletogenesis and muscle replacement are delayed until tail outgrowth is underway. We demonstrate that tail regeneration is an example of epimorphic regeneration. Furthermore, we show that the transcription factor Sox9 is involved in cartilage regeneration. A role for the morphogen Shh remains inconclusive. Ongoing studies will provide an important complement for regeneration research by expanding the comparative framework.