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

Stellate lumen

Tissue layers of wall

Trachea Oesophagus

Tissue Layers

Lumen

Mucosa

Muscularis Externa

Adventitia

Submucosa

Mucosa

Non-keratinised stratified squamous epithelium

Lamina propria

Muscularis mucosa

Lumen

Blood vessel

Lymphatic nodule in lamina

propria

Oesophageal submucosal gland

Blood vessels

Irregular dense connective tissue

Mucosa

Submucosa

Submucosa Note: Meissner’s plexus found in submucosa

Cystic duct of gland

Basophilic lymphoid tissue

Muscularis Externa

Submucosa

Muscularis externa Inner circular layer

Muscularis externa Outer longitudinal layer

Note: Upper 1/3 = skeletal m., Middle 1/3 = skeletal & smooth m., Lower 1/3 = smooth m. Note: Auerbach plexus found between m. layers

Adventitia

Adventitia

Muscularis externa

No mesothelium

STOMACH

• Slide 81 Stomach (Fundus) – H&E stain

Mucosa Submucosa Muscularis Externa Serosa

Structure Rugae

Tissue layers of wall

Lumen

Tissue Layers

Lumen

Mucosa

Muscularis Externa

Serosa

Submucosa

Mucosa

Mucosa

Lumen

Gastric pit lined by simple columnar epithelium

Muscularis mucosa

Submucosa

Lymphoid tissue of lamina propria

Fundic glands

Glands

Columnar mucus- secreting cells Parietal cells

Chief cells

Mucosa

Submucosa

Mucosa

Submucosa

Blood vessels

Meissner’s plexus

Muscularis Externa

Submucosa

Muscularis externa with inner oblique, middle circular and outer longitudinal layers

Auerbach plexus

Serosa

Muscularis externa

Serosa

Mesothelium

SMALL INTESTINE

• Slide 84 Duodenum – H&E stain

Mucosa Submucosa Muscularis Externa Adventitia & Serosa

Structure

Tissue layers of wall

Lumen

Plicae circulares with core of submucosa

Villi

Tissue Layers

Lumen Mucosa

Adventitia / Serosa Submucosa

Muscularis Externa

Mucosa

Muscularis mucosa

Lamina propria extending into villi

Simple columnar epithelium with microvillus border

covering villus

Peyer’s patches in lamina propria

Glands

Goblet cells

Crypts of Lieberkϋhn opening between two villi

Villi

Brunner’s gland

Secretory units of Brunner’s glands

Columnar cells with apical microvilli

Submucosa

Submucosa

Blood vessels

Brunner’s gland

Mucosa

Muscularis Externa

Serosa

Submucosa

Muscularis externa inner circular layer

Muscularis externa outer longitudinal layer

Auerbach plexus

LARGE INTESTINE

• Slide 91 Colon – H&E stain

Mucosa Submucosa Muscularis Externa Serosa

Structure

Tissue layers of wall

Lumen

Taenia coli

Tissue Layers

Lumen

Muscularis Externa

Serosa

Mucosa Submucosa

Mucosa

Mucosa

Simple columnar epithelium with apical microvilli

Goblet cells

Muscularis mucosa

Lamina propria

Submucosa

Submucosa

Submucosa

Blood vessels

Mucosa

Muscularis Externa

Muscularis externa inner circular layer

Muscularis externa outer longitudinal layer