The “Road Map”
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