Assertion: zygote's cell | /r/CapableOf | migrate to form the three layers of cells
Facets:
value: with a hollow space
type: OTHER
Source sentences:
text: During gastrulation, the blastula folds in on itself and cells migrate to form the three layers of cells (Figure 13.10) in a structure, the gastrula, with a hollow space that will become the digestive tract.