Within an hour of ingression, numerous transcript factors are activated. Cytokinetic furrow ingression is powered by Type II Myosin ATPase. Important to the sea urchin blastula is the ingression of the primary mesenchyme. Ingression of these cells results in formation of the mesoderm. Like the Whiteheadian ingression, the "distribution without dividing" is a rethinking of the Platonic participation.