Membranous sheet attaching various organs to the body wall, especially the peritoneal fold attaching the intestine to the dorsal body wall.
Source:
PAC, 2016, 88, 713. 'Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)' on page 778 (https://doi.org/10.1515/pac-2015-1202)