organizational grouping of cells during pre-embryonic development into ectoderm, mesoderm, endoderm
distinct layers of cells, produced during the early embryonic developmental process of gastrulation, which gives rise to all cells, tissues, organs, and organ systems of the organism's body. The three types of germ layers are the ectoderm, endoderm, and mesoderm. Diploblastic organisms (e.g. cnidarians) have two layers, ectoderm and endoderm; triploblastic organisms (all higher animal groups) have mesoderm between these two layers
in the second and third week of development, the first three cellular layers (ectoderm, mesoderm, and endoderm) that will faorm all tissues of the embryo. Named originally by Robert Remak (1815 - 1865) a German scientist and embryologist. (More? Week 2 Notes Week 3 Notes | Robert Remak)
The three initial tissue layers arising in the embryoâ€” endoderm, mesoderm, and ectodermâ€”from which all other somatic tissue-types develop.
The three layers formed marks the end of early development and beginning of cell migration and determination
germinis - a bud, offshoot]. The three major cellular layers (ectoderm, mesoderm, endoderm) which are laid down in the embryo during gastrulation. Each layer is the precursor of different tissues and organs.