Epithelial fusion is mediated by a partial epithelial–mesenchymal transition

Abstract

Epithelial fusion is a fundamental morphogenetic process critical for the closure and compartmentalisation of developing organs. While widely studied in systems such as neural tube and palatal closure, the cellular transitions that enable fusion remain poorly understood. Here, we investigate epithelial fusion during chick otic vesicle closure and identify a transient population of cells at the epithelial interface that mediate this process. These otic epithelial edge (OE) cells exhibit distinct morphology, reduced apicobasal polarity, and dynamic junctional remodelling, including altered distribution of ZO-1, CDH1 and RAC1.