Gastraea | ‖n. [ NL., from Gr. &unr_;, &unr_;, the stomach. ] (Biol.) A primeval larval form; a double-walled sac from which, according to the hypothesis of Haeckel, man and all other animals, that in the first stages of their individual evolution pass through a two-layered structural stage, or gastrula form, must have descended. This idea constitutes the Gastræa theory of Haeckel. See Gastrula. [ 1913 Webster ] |
Gastrula | ‖n.; |
Gastrulation | n. (Biol.) The process of invagination, in embryonic development, by which a gastrula is formed. [ 1913 Webster ] |
gastrulate | |
gastrulation |
gastrula | (n) double-walled stage of the embryo resulting from invagination of the blastula; the outer layer of cells is the ectoderm and the inner layer differentiates into the mesoderm and endoderm |
gastrulation | (n) the process in which a gastrula develops from a blastula by the inward migration of cells |
Gastrula | ‖n.; |
Gastrulation | n. (Biol.) The process of invagination, in embryonic development, by which a gastrula is formed. [ 1913 Webster ] |