midgut

synonym: mesenteron
https://doi.org/10.1351/goldbook.10965

Middle section of the digestive tract in a vertebrate embryo, from which the ileum, jejunum, and portions of the duodenum and colon develop.

Source:
PAC, 2016, 88, 713. (Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)) on page 780 [Terms] [Paper]