Cell movements in the sea urchin embryo.

Recent studies show that gastrulation in the sea urchin embryo involves movement of cells over the blastopore lip (involution). Some cells in the vegetal plate of the late blastula become bottle-shaped but they play a limited role in gastrulation. The functions of specific integrins, regulators of cell-cell adhesion, and extracellular matrix components in gastrulation are currently being analyzed. In addition, light-microscopic studies continue to provide a unique picture of dynamic cell behavior in vivo.