PRACTICAL ROADMAP DIGESTIVE SYSTEM WJ van der Spuy LAYERS OF DIGESTIVE TRACT • Mucosa – Lining Epithelium (glands derived) – Lamina Propria (connective tissue & lymphatic tissue) – Muscularis Mucosa (smooth muscle) • Submucosa – (connective tissue, blood & lymphatic vessels, nerve plexus & sometimes glands) • Muscularis Externa – (inner circular & outer longitudinal smooth muscle) • Adventitia / Serosa – (connective tissue / connective tissue & mesothelium) OESOPHAGUS • Slide 32 Oesophagus – H&E stain Mucosa Submucosa Muscularis Externa Adventitia Structure Oesophagus Trachea Tissue layers of wall Stellate lumen Tissue Layers Lumen Mucosa Submucosa Muscularis Externa Adventitia Lymphatic nodule in lamina Mucosa propria Blood vessel Lamina propria Lumen Muscularis mucosa Non-keratinised stratified squamous epithelium Cystic duct of gland Submucosa Note: Meissner’s plexus found in submucosa Irregular dense connective tissue Oesophageal submucosal gland Basophilic lymphoid tissue Submucosa Mucosa Blood vessels Muscularis Externa Note: Upper 1/3 = skeletal m., Middle 1/3 = skeletal & smooth m., Lower 1/3 = smooth m. Note: Auerbach plexus found between m. layers Submucosa Muscularis externa Inner circular layer Muscularis externa Outer longitudinal layer Adventitia Muscularis externa Adventitia No mesothelium STOMACH • Slide 81 Stomach (Fundus) – H&E stain Mucosa Submucosa Muscularis Externa Serosa Structure Lumen Rugae Tissue layers of wall Tissue Layers Lumen Mucosa Submucosa Muscularis Externa Serosa Mucosa Gastric pit lined by simple columnar epithelium Lymphoid tissue of lamina propria Lumen Fundic glands Submucosa Mucosa Muscularis mucosa Glands Columnar mucus- secreting cells Parietal cells Mucosa Chief cells Submucosa Meissner’s plexus Mucosa Blood vessels Submucosa Muscularis Externa Auerbach plexus Submucosa Muscularis externa with inner oblique, middle circular and outer longitudinal layers Serosa Muscularis externa Mesothelium Serosa SMALL INTESTINE • Slide 84 Duodenum – H&E stain Mucosa Submucosa Muscularis Externa Adventitia & Serosa Plicae circulares with core of Structure submucosa Lumen Villi Tissue layers of wall Tissue Layers Lumen Mucosa Muscularis Externa Submucosa Adventitia / Serosa Mucosa Peyer’s patches in lamina propria Simple columnar epithelium with microvillus border covering villus Muscularis mucosa Lamina propria extending into villi Glands Villi Columnar cells with apical microvilli Goblet cells Secretory units of Crypts of Lieberkϋhn Brunner’s glands opening between two villi Brunner’s gland Submucosa Mucosa Blood vessels Submucosa Brunner’s gland Muscularis Externa Submucosa Auerbach plexus Muscularis externa inner circular layer Muscularis externa outer longitudinal layer Serosa LARGE INTESTINE • Slide 91 Colon – H&E stain Mucosa Submucosa Muscularis Externa Serosa Structure Lumen Tissue layers of wall Taenia coli Tissue Layers Lumen Mucosa Submucosa Muscularis Externa Serosa Mucosa Simple columnar epithelium Goblet cells with apical microvilli Mucosa Lamina propria Muscularis mucosa Submucosa Submucosa Blood vessels Submucosa Mucosa Muscularis Externa Muscularis externa outer longitudinal layer Muscularis externa inner circular layer .