An embryo at the stage following the blastula, when it is a hollow cup-shaped structure having three layers of cells.
- ‘For example, most metazoans go through a developmental stage called a gastrula - a ball of cells with an infolding that later forms the gut.’
- ‘During gastrulation, cells on the outside of the embryo move inwards and, in animals such as the sea urchin, gastrulation even transforms a hollow spherical blastula into a gastrula with a hole through the middle - the gut.’
- ‘Gastrulation in its broadest sense is the reorganization of the cells of the blastula to form a multilayered embryo, the gastrula.’
- ‘Using light microscopy, he concluded that the embryo underwent gastrulation and that the gastrula consisted of three ‘cell elements’ on the outside, and two on the inside.’
- ‘The nucleus must be taken from the blastula and gastrula stages of frog embryos (at this point no semblance or form of the creature is distinguishable).’
Late 19th century: modern Latin, from Greek gastēr, gastr- stomach + the Latin diminutive ending -ula.