mesenteron

In embryology, the interior of the archenteron or primitive intestine; the intestinal cavity in an early stage, bounded by the hypoblast.

In sea-anemones and similar polyps, the main digestive cavity or stomach; in Mollusca, the stomach and intestine. Compare stomodæum and proctodæum.

All that part of the alimentary canal which is developed from the primitive enteron and is lined with hypoblast. It is distinguished from the stomodæum, a part at the anterior end of the canal, including the cavity of the mouth, and the proctodæum, a part at the posterior end, which are formed by invagination and are lined with epiblast.

The midgut.