Origin and shaping of the laterality organ in zebrafish
Abstract
Handedness of the vertebrate body plan critically depends on transient embryonic structures/organs that generate cilia-dependent
leftward fluid flow within constrained extracellular environments. Although the function of ciliated organs in laterality
determination has been extensively studied, how they are formed during embryogenesis is still poorly understood. Here we show
that Kupffer’s vesicle (KV), the zebrafish organ of laterality, arises from a surface epithelium previously thought to adopt exclusively
extra-embryonic fates. Live multi-photon confocal imaging reveals that surface epithelial cells undergo Nodal/TGFβ signallingdependent
ingression at the dorsal germ ring margin prior to gastrulation, to give rise to dorsal forerunner cells (DFCs), the
precursors of KV. DFCs then migrate attached to the overlying surface epithelium and rearrange into rosette-like epithelial
structures at the end of gastrulation. During early somitogenesis, these epithelial rosettes coalesce into a single rosette that
differentiates into the KV with a ciliated lumen at its apical centre. Our results provide novel insights into the morphogenetic
transformations that shape the laterality organ in zebrafish and suggest a conserved progenitor role of the surface epithelium
during laterality organ formation in vertebrates.
Patrocinador
This work was supported
by grants from the DFG, MPG and EU to C.-P.H., from the PBCT (ACT47),
CONICYT/DAAD (2003-4-124), MIDEPLAN (ICM P04-068-F), HHMI
(INTNL55005940) and EU (FP6-NEST-PATH EDCBNL) to M.L.C., and from the
Proyecto Mecesup UCH0306 and DAAD to P.O.
Quote Item
Development, vol. 135, issue 16, p. 2807-2813, 2008.
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