Histology for Pathology Gastrointestinal System and Exocrine Pancreas

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Histology for Pathology Gastrointestinal System
and Exocrine Pancreas

• Theresa Kristopaitis, MD
• Associate Professor
• Director of Mechanisms of Human Disease
• Kelli A. Hutchens, MD, FCAP
• Assistant Professor
• Assistant Director of Mechanisms of Human Disease
• Loyola Stritch School of Medicine

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Objectives

• On HE stained sections, identify the four
  general layers of the digestive tract organs
  (esophagus, stomach, small bowel, colon) Mucosa
  submucosa muscularis externa, and
  adventitia/serosa
• On HE stained sections identify the following
  components of the mucosa epithelium, lamina
  propria, muscularis mucosa
• Describe the components of the submucosal layer
  of the digestive organs
• Explain the location of Meissner plexus vs
  Auerbach plexus and describe the function of each
• Name the type of epithelium comprising the
  mucosa of the esophagus, stomach, small bowel,
  appendix, colon and anal canal.
• Identify submucosal glands in the esophagus and
  describe their function.
• Describe the composition of the esophagogastric
  junction
• Name the four parts of the stomach.
• Identify gastric pits and explain their function.
• On high power HE stained sections distinguish
  parietal cells from chief cells. List the
  substances secreted by each of the cells.

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Objectives

• Identify the following key components of the
  small intestine
• Duodenum villi, Brunner glands
• Jejunum villi, goblet cells
• Ileum villi, goblet cells, Peyer patches
• Define Crypts (or Glands) of Lieberkuhn.
• Contrast vili vs plicae circulares
• On HE stained sections distinguish colon from
  small intestine.
• Define taenia coli.
•  In HE stained sections of pancreas distinguish
  the endocrine components of the pancreas from the
  exocrine components.
•  In HE stained sections of pancreas identify
  pancreatic acinar cells vs ducts.

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Oral Cavity

• Inner surface of the lips, cheeks, soft palate,
  surface of tongue, and floor of the mouth
• Nonkeratinized stratified squamous epithelium
• Lamina propria
• Submucosa
• Gingiva and hard palate
• Keratinized stratified squamous epithelium
• Lamina propria
• Tongue specialized mucosa with papillae

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Digestive Tract

• Comprised of hallow organs
• Esophagus
• Stomach
• Small intestine
• Large intestine
• Histologic organization
• Mucosa
• Epithelium, lamina propria, muscularis mucosa
• Submucosa
• connective tissue, vessels, and Meissners
  plexuses, some times mucous glands
• Muscularis externa 2-3 layers of smooth muscle
  (plus skeletal muscle in esophagus), myenteric
  (Auerbach) plexus in between muscle layers
• Serosa and adventitia Outermost layer of loose
  connective tissue and blood vessels. Call serosa
  if covered my mesothelium adventitia otherwise

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Esophagus

• Mucosa non-keratinizing stratified squamous
• Submucosa contains mucous glands
• Increased mucous glands at lower esophagus (GE
  junction) to protect esophagus from gastric
  juices
• Muscularis externa inner circular and outer
  longitudinal
• Contains skeletal muscle fibers

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Esophagus
Squamous mucosa
Submucosa
Muscularis Externa
Mucosa
Muscularis mucosa
Adventitia / Serosa
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Gastric-Esophageal Junction(Esophagogastric
junction)
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Stomach

• Anatomically and histologically divided into
  cardia, fundus body, and pylorus
• Cardia first section separate from esophagus
  by cardiac sphincter. Glands contain
  mucus-secreting cells, stem cells,
  enterendocrine, and occasional parietal cells
• Fundus and body largest portion. Fundic glands
  contain parietal cells and chief cells with some
  stem cells, mucous cells and enteroendocrine
  cells
• Pyloric region lower end that connects to
  duodenum ends at pyloric sphincter. Glands
  primarily mucus-secreting cells and two special
  endocrine cells gastrin-secreting (G cells) and
  somatostatin-secreting cells (D-cells)

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Mucosa of the Stomach
Columnar Epithelium
Gastric Pit
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Fundic Mucosa
Parietal Cells secrete HCL
Fundic Gland
Chief Cells secret zymogen granules containing
pepsinogen
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Small Intestine

• Major site for absorption of nutrients and its
  mucosa is made for this!
• Villi and microvilli
• Glands (crypts) of Lieberkuhn in lamina propria
  that open into the mucosa at the base of villi.
• Paneth cells with pink granules at the base of
  the crypts secrete lysozymes, tumor necrosis
  factor-alpha, and defensins.
• Submucosa with Meissner plexus
• Three sections
• Duodenum Brunner glands (mucus secreting)
• Jejunum long villi and increased goblet cells
  no Brunner glands or Peyer patches
• Ileum Short villi, many goblet cells, and
  lymphatic nodules in the submucosa called Peyer
  patches

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Duodenum
Mucosa
Brunners Glands
Paneth Cells
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Jejunum
Goblet Cells
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Ileum
Paneth Cells
Peyers patches
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Small Intestine Paneth Cells
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Small Intestine
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Large Intestine

• Major site of absorption of water and salts
• Mucosa No villi, gland of Lieberkuhn with many
  goblet cells and no paneth cells.
• Submucosa no glands
• Muscularis externa Inner circular muscle plus
  outer longitudinal muscle with myenteric
  (Auerbach) plexus between.
• Outer longitudinal muscle creates three narrow
  bands called tenia coli.
• Four anatomic sections
• Cecum
• Appendix
• Colon
• Rectum and anal canal

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Large Intestine Mucosa
Goblet Cells
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Colon Wall
Muscularis externa (circular portion)
Mucosa
Submucosa
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Muscularis Externa
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Appendix
Lymphatic Nodules
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Anal -Rectal Junction
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Exocrine Pancreas

• Many serous secretory cells (pancreatic acinar
  cells) form acinar structures.
• Cytoplasm contains zymogen granules
• Secretions carried by main duct to join bile duct
  at the ampulla in the duodenum

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Main pancreatic duct and surrounding acini
Main Duct
Pancreatic Acini