For 10 points, the archenteron, or digestive cavity, appears during what stage of embryonic development that is a double-walled sphere formed after cells have invaginated from the blastula stage?
During this process in amphibians, convergent extension at the marginal zone helps to determine the anterior-posterior axis. Its two general methods are epiboly and emboly, the former of which is utilized heavily by creatures with large, yolky eggs. Consisting of three layers of cells, clusters of cells called organizers begin to produce molecular signals to induce other cells to different fates. For 10 points, the archenteron, or digestive cavity, appears during what stage of embryonic development that is a double-walled sphere formed after cells have invaginated from the blastula stage?
During this process in amphibians, convergent extension at the marginal zone helps to determine the anterior-posterior axis.
{Gastrula} or {Gastrulation}