1. gastrula - Noun
2. gastrula - Adjective
An embryonic form having its origin in the invagination or pushing in of the wall of the planula or blastula (the blastosphere) on one side, thus giving rise to a double-walled sac, with one opening or mouth (the blastopore) which leads into the cavity (the archenteron) lined by the inner wall (the hypoblast). See Illust. under Invagination. In a more general sense, an ideal stage in embryonic development. See Gastraea.
Of or pertaining to a gastrula.
Source: Webster's dictionaryAn ancestral form existed, known as the gastrea, which was a common ancestor to the corresponding gastrula. Source: Internet
Haeckel portrays a concrete demonstration of his Biogenetic Law through his ‘Gastrea’ theory, in which he argues that the early cup-shaped gastrula stage of development is a universal feature of multi-celled animals. Source: Internet
The parts that are autotomised or the buds may develop directly into fully formed larvae or may develop through a gastrula or even a blastula stage. Source: Internet