Gastrulation in Amphibians:
Migratory Cues for Leading Edge Cells
The leading edge of the mesoderm migrates along the blastocoel roof as gastrulation proceeds. Experiments in the salamander, Pleurodeles waltii, indicate that fibronectin plays a key role in supporting migration of the leading edge. Injection of anti-fibronectin antibodies or sequences that compete for binding of fibronectin to its normal receptor (a heterodimeric protein formed from members of the integrin family of extracellular matrix receptors) disrupt leading edge migration and hence involution. Examine the micrographs at the right, which show both normal and experimentally perturbed salamander embryos to see how disruption of attachment to fibronectin can have drastic effects on involution.
Interior of normal gastrula
Interior of RGD-injected gastrula
Exterior of normal gastrula
Exterior of RGD- injected embryo