Gastrulation: Making and Shaping Germ Layers
Annual Review of Cell and Developmental Biology
Vol. 28: 687-717 (Volume publication date November 2012)
First published online as a Review in Advance on July 9, 2012
DOI: 10.1146/annurev-cellbio-092910-154043
Lila Solnica-Krezel and Diane S. Sepich
Department of Developmental Biology, Washington University School of Medicine in St. Louis, St. Louis, Missouri 63110; email: solnical@wustl.edu, sepichd@wustl.edu
Abstract
Gastrulation is a fundamental phase of animal embryogenesis during which germ layers are specified, rearranged, and shaped into a body plan with organ rudiments. Gastrulation involves four evolutionarily conserved morphogenetic movements, each of which results in a specific morphologic transformation. During emboly, mesodermal and endodermal cells become internalized beneath the ectoderm. Epibolic movements spread and thin germ layers. Convergence movements narrow germ layers dorsoventrally, while concurrent extension movements elongate them anteroposteriorly. Each gastrulation movement can be achieved by single or multiple motile cell behaviors, including cell shape changes, directed migration, planar and radial intercalations, and cell divisions. Recent studies delineate cyclical and ratchet-like behaviors of the actomyosin cytoskeleton as a common mechanism underlying various gastrulation cell behaviors. Gastrulation movements are guided by differential cell adhesion, chemotaxis, chemokinesis, and planar polarity. Coordination of gastrulation movements with embryonic polarity involves regulation by anteroposterior and dorsoventral patterning systems of planar polarity signaling, expression of chemokines, and cell adhesion molecules.
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CITAÇÃO FAMOSA
"Não é o nascimento, casamento ou morte, mas a gastrulação, que é verdadeiramente o tempo mais importante em sua vida". Lewis Wolpert, embriologista britânico.
"It is not birth, marriage or death, but gastrulation, which is truly the most important time in your life". British embryologist Lewis Wolpert.
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