Linking organ formation to left-right patterning in the embryonic zebrafish

While the function of patterning in organogenesis is being extensively studied, considerably less is known of reverse effects that organ formation imposes on patterning. In zebrafish, the Kupffer’s vesicle (KV) and parapineal (PP) are embryonic struc- tures that share mechanisms of organogenesis and whose func- tion is essential for normal patterning along the left–right axis. Early morphogenesis of KV and PP organs involve the compaction of progenitor cells into a tight cluster within which three-dimen- sional cellular rosettes are formed. Organisation into rosettes pre- cedes the detachment of progenitor cells from neighbouring tissue and thus represents a key step towards organ formation. Such morphogenetic event is essential for organ function and its disruption has profound effects on left–right patterning.