Fig. 4

Development of the zebrafish Kupffer’s vesicle as a model to investigate mechanisms that control EMT and MET. A Schematic of Kupffer’s vesicle development in zebrafish. Boxes on embryo diagrams on the left indicate location of cells depicted on the right. At 6 h post-fertilization (hpf), precursor cells called dorsal forerunner cells (DFCs) are specified at the dorsal margin. Mesenchymal DFCs migrate and then form a rosette structure at 10 hpf. DFCs undergo MET to form the epithelial Kupffer’s vesicle (KV). A cross section through the KV depicts epithelial cells lining a fluid-filled lumen at 12 hpf. After KV functions to establish the left–right body axis, KV collapses at 18 hpf and the epithelial cells undergo EMT and migrate away. B Confocal microscopy images of live transgenic Tg(sox17:GFP-CAAX) embryos that express membrane-targeted GFP in DFC and KV cells at developmental stages corresponding to diagrams in A. The planar cell polarity (PCP) proteins Prickle 1a (Pk1a) and Wnt11 regulate cell–cell adhesion between DFCs during MET and rosette formation [67]. Mechanisms that control KV breakdown and EMT of KV cells remain unknown