Dynamic Interplay of Epithelial–Mesenchymal and Mesenchymal–Epithelial Transitions in Cochlear Development and Disease: Molecular Mechanisms and Therapeutic Implications

Epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET) are evolutionarily conserved cellular processes defined by reversible conversions between epithelial and mesenchymal phenotypes. As dynamic regulatory programs, they contribute to cell fate determination, tissue remodeling, and functional maturation during embryogenesis. In the cochlea, emerging evidence suggests that EMT/MET are implicated in certain aspects of sensory epithelium development. This review systematically dissects the molecular mechanisms underlying EMT and MET during cochlear development, along with the regulatory networks that control cell fate and signaling pathways. We further explore the emerging functions of these processes in cochlear pathologies, integrating recent advances to clarify their physiological and pathological relevance. By providing a comprehensive synthesis, this work aims to establish a theoretical framework for developing therapeutic strategies against related disorders.