3D to Late Prism
© 1998 Chris Patton, Stanford University

A 3D representation of development in the sea urchin from the one cell to the late prism stage.

Note the micromeres are highlighted in red. The micromeres are essential for gastrulation.

At the prism stage the free swimming embryo starts to feed.

Remember, in deuterostomes, the anus forms first and then the mouth.