Regeneration and development. An amphibian call to arms

Area of Science:

• Developmental Biology
• Regenerative Medicine
• Amphibian Biology

Background:

• The newt Notophthalmus viridescens undergoes two metamorphoses, transitioning from aquatic larvae to terrestrial adults.
• Limb regeneration in larval and adult stages is often considered similar and a recapitulation of embryonic development.

Purpose of the Study:

• To compare larval limb development with the regeneration of both larval and adult forelimbs in Notophthalmus viridescens.
• To investigate differences in developmental patterns between larval and adult limb regeneration.

Main Methods:

• Morphological comparison of limb development and regeneration.
• Analysis of digit formation patterns in larval and adult regenerates.

Main Results:

• Substantial differences exist in limb development patterns between larval and adult stages.
• Adult limb regeneration lacks the preaxial dominance seen in larvae, with synchronous digit development.
• Larval regenerates exhibit sequential digit formation, mirroring embryonic limb bud development.

Conclusions:

• Larval limb regeneration is likely a form of developmental regulation, not epimorphic regeneration seen in adults.
• Post-metamorphic limb regeneration is not a simple morphological recapitulation of embryonic development.
• These findings clarify regeneration differences in neotenic or paedomorphic urodeles.