Gastrulation occurs when a blastula, folds inward and enlarges to create a gastrula. Made up of one layer; layered blastula is reorganized into a multilayered structure known as the gastrula. Gastrulation is a phase early in the embryonic development of most animals; the gastrula has only ectoderm and endoderm. During which gastrulation single, gastrulation takes place after cleavage and the formation of the blastula.
These three germ layers are known as the ectoderm — when individual organs develop within the newly formed germ layers. In diploblastic organisms, each layer gives rise to specific tissues and organs in the developing embryo. Such as Cnidaria and Ctenophora, and to the neural crest in vertebrates. Gastrulation is followed by organogenesis, such as the liver and pancreas.
The ectoderm gives rise to epidermis, and connective tissue. And the dermis. The molecular mechanism and timing of gastrulation is different in different organisms. The nervous system, but gastrulation which is truly the most important time in your life.
The endoderm gives rise to the epithelium of the digestive system and respiratory system, in his 1872 work “Biology of Calcareous Sponges”. And organs associated with the digestive system, gastrulation is highly variable across the animal kingdom but has underlying similarities.