noun, plural e·pib·o·lies. Embryology.
- the movement and spreading out of cells into sheets of tissue that overlie or surround other groups of cells, especially as in the formation of certain gastrulas.
noun plural -lies
- embryol a process that occurs during gastrulation in vertebrates, in which cells on one side of the blastula grow over and surround the remaining cells and yolk and eventually form the ectoderm
- The growth of a rapidly dividing group of cells around a more slowly dividing group of cells, as in the formation of a gastrula.