"Endoderm" Quotes from Famous Books
... condition of the vertebrate alimentary canal may be described as a straight, simple tube, consisting of an anterior portion, the stomodaeum, formed by an ectodermal invagination, the mesenteron, a long median portion lined by endoderm, and a short posterior portion, the proctodaeum, formed by ectodermal invagination. In the lower vertebrates the primitive tube subserved also the purpose of respiration, and traces of the double function remain in the adult structure of all vertebrates (see MOUTH, PHARYNX.) In fish, ... — Project Gutenberg Encyclopedia |