— gastrular , adj.
/gas"troo leuh/ , n. , pl. gastrulas, gastrulae /-lee'/ . Embryol.
a metazoan embryo in an early state of germ layer formation following the blastula stage, consisting of a cuplike body of two layers of cells, the ectoderm and endoderm, enclosing a central cavity, or archenteron, that opens to the outside by the blastopore: in most animals progressing to the formation of a third cell layer, the mesoderm.
[ 1875-80; ]