Epimorphosis

Definition

A mode of regeneration in which lost tissues or structures are restored through localized cell proliferation, involving dedifferentiation of nearby cells, blastema formation, and subsequent redifferentiation to reconstruct the original anatomy and polarity. Unlike morphallaxis, epimorphosis depends on substantial new growth at the wound site rather than remodeling of existing tissues.

Etymology

From Greek epi- (upon) + morphē (form) + -osis (process), referring to the new formation of structure upon the site of injury.

Example

Many insects and arachnids exhibit epimorphosis when regenerating legs: after autotomy, a blastema forms at the wound, and through successive molts the limb is progressively restored to its original size and segmentation pattern.

Synonyms

• epimorphic regeneration

Related Terms

• morphallaxis
• blastema
• dedifferentiation
• Autotomy
• Regeneration
• molting
• stem cell

Usage Notes

Contrasts with morphallaxis, where regeneration occurs through repatterning of existing cells without extensive proliferation. In arthropods, epimorphosis is often iterative—regenerated appendages may require multiple molts to attain full size. The term is sometimes used more broadly in developmental biology, but in entomology it specifically describes the blastema-dependent process seen in limb and antenna regeneration.