Mesoderm Induction and Patterning
The mesoderm arises prior to gastrulation as a ring at the equator of the embryo (Fig. 1A). This ring of cells sits on top of an extra embryonic structure called the yolk syncytial layer (YSL). The YSL forms when the most marginal blastomeres collapse into the yolk cell at the 10th cleavage (Kimmel and Law 1985b). The cells closest to the YSL develop into either mesoderm or endoderm, whereas cells further away from the YSL develop only as mesoderm (Kimmel et al. 1990; Warga and Nusslein-Volhard 1999).
KeywordsNodal Signaling Activin Receptor Convergent Extension Mesoderm Induction Yolk Syncytial Layer
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