Morphology and histology of the jejunum and ileum János Hanics M.D. Anatomy of the pancreas and duodenum Duodenojejunal flexure Ileocoecal junction Bauchin - valve Jejunum and ileum are intraperitoneal organs The peritoneum is the largest serous membrane of the human body. Derives from lateral plates of mesoderm. It has two layers: 1. parietal peritoneum 2. visceral peritoneum They have a continuous mesothelial layer Abdominal and pelvic organs and structures – according to their peritoneal relations - can be divided into 2 main groups: Intraperitoneal - covered by peritoneum and generally they have a duplication Extraperitoneal (not surrounded by the peritoneum) within this: - Praeperitoneal - Retroperitoneal (secunder and primary) - Infraperitoneal structures. Duplication = meso- !!!! 1 4 3 2 5 1. Stomach mesentery 2. Transverse colon 3. Duodenum 4. Pancreas 5. Jejunum, ileum Mesentery (root of mesentery) mesenterial antimesenterial Development Ventral mesentery Dorsal mesentery Unpaired visceral branches of the abdominal aorta Branches of the sup. mes. a. System of the portal vein Cysterna chyli and thoracic duct Innervation: parasympathetic (vagus) and sympathetic Tunica mucosa Histology of the small interstine - (E)Epithelium (simple cuboideal) - (LPM)Lamina propria mucosae - (LMM)Lamina muscularis mucosae Tela submucosa Tunica muscularis - Circular layer (inner) - Myenteric plexus (Auerbachi) - Longitudinal layer (outer) Tela subserosa Tunica serosa (mesothelium) - Circular folds (Kerckring’s) - Intersinal villi - Microvilli (3000/cell) Longitudinal section – circular folds (plicae circulares=Kerckring’s folds) Interstinal villi Lieberkühn -crypts Intersinal villus In LPM MALT (GALT) Enterocyte Enterocyte Lieberkühn-crypts (interstinal glands) Cells in the wall of Lieberkühn-crypts (interstinal glands) Lysozyme production Regeneration Duodenum Jejunum Ileum Tunica mucosa Tela submucosa!!! Brunner’s glands (FLA) Peyer’s patches (antimesenterial margin!!!) Tunica muscularis Tela subserosa Tunica serosa Jejunum Duodenum Ileum (FLA) Folliculi lymphatici aggregati – Peyer’s patches FLA Tunica muscularis (myenteric plexus of Auerbach Thank You for Your attention!.