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!