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 (https://doi.org/10.1515/pac-2015-1202)