Epiboly arrests briefly and then continues after formation of the embryonic shield.  
During this phase, Brachet's cleft becomes visible between the epiblast and the hypoblast.  Epiboly arrests briefly and then continues after formation of the embryonic shield.  Its primary characteristic is the archenteron, which eventually forms the cavity of the gut and is connected to the outside by the blastopore, which becomes either an animal's mouth or anus.  The primary germ layers are also formed during this stage of development.  FTP, identify this stage of embryonic development that follows the blastula.
During this phase, Brachet's cleft becomes visible between the epiblast and the hypoblast.  
gastrula