Epimorphózis

Epimorphózis, also known as epimorphosis, is a mode of post-embryonic development and tissue regeneration in which a proliferative cell mass called a blastema forms at the site of injury. The term derives from Greek epi meaning “upon” and morphosis meaning “form.” In epimorphosis, mature cells near the wound can dedifferentiate or resident stem/progenitor cells become activated, proliferate, and generate a blastema that differentiates to reconstruct missing tissues and organs. The resulting structure is built through patterning and growth that restore the original morphology and size.

Key features include a reliance on cell proliferation within the blastema and subsequent differentiation to recreate complex structures, often with correct tissue organization and axes. Patterning signals guide the developing tissues to form a structurally appropriate replacement. Epimorphosis is typically contrasted with morphallaxis, in which regeneration proceeds mainly by remodeling existing tissues with little cell proliferation and without blastema formation.

Examples and occurrences include the limb and fin regeneration observed in amphibians and fish, such as salamanders forming a blastema to regrow limbs and zebrafish regenerating fins. Planarian flatworms also use an epimorphic-like process, with neoblasts proliferating to replace lost parts. Epimorphosis is a central concept in regenerative biology and developmental biology, informing how organisms restore form after injury and how signals controlling dedifferentiation, proliferation, and patterning operate across species.