Histology of the GI tract

Question 1

Describe the histology of the Oesophagus

Answer 1

• Stratified squamous non-keratinised epithelium
  
  • Submucosa shows mucous glands (lubrication)
    
    • Muscular layer: upper 1/3 skeletal, middle 1/3 smooth+ skeletal, lower 1/3 smooth

Question 2

Describe the histology of the Stomach

Answer 2

• Parietal cells (pink stain): NaCl
  
  • Chief cells at the base of the gland: pepsinogen
  • Simple columnar epithelium
  • Gastric glands in mucosa (above muscularis mucosae)
  • 3 layers of muscles in muscularis externa (if you can see this layer in the micrograph)

Question 3

Describe the histology of the small intestine

Answer 3

• Villi
  
  • Crypts of Lieberkühn: secrete water and NaCl
    • Duodenum
  • Brunner’s gland in submucosa: secrete bicarbonate
    • Ilium
  • Peyer’s patches: Lymphoid aggregations in the mucosa
  • Villi
    • Jejunum
  • Neither Brunner’s gland or Peyer’s patches (or very little)

Question 4

Describe the histology of the large intestine

Answer 4

• Thick mucosa
  
  • Crypts
  • Mucous secreting cells
  • No villi

Question 5

Describe the histology of secretory cells

Answer 5

• Secretory acini (roundish structure with columnar cells and nuclei at the base)
  
  • Ducts

Question 6

Describe the histology of the pancreas

Answer 6

• Islets of Langerhans
  
  • Pancreatic acini
    
    • Pancreatic duct

Question 7

Describe the histology of the liver

Answer 7

• Central vein
  
  • Portal triad: Hepatic artery, portal vein and hepatic bile duct
  • Septa