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GI Tract Histology

  • The entire GI tract from the esophagus to the anus possesses the same basic histological layers. Depending on the particular segment, certain layers may be more or less prominent, or possess specialized features as required for their unique functionality. We first present an overview of the three basic GI tract layers and then discuss the unique histological features of particular segments on their own pages.
Basic Layers
  • GI Mucosa: Itself made of three layers
    • GI Epithelium: The morphology and architecture of the GI Epithelium changes radically between different segments of the GI tract, correlating with changes in the functionality of these different segments in terms of digestion, absorption, and secretion.
    • GI Lamina Propria: A largely collagenous mesh which supports the GI epithelium and often contains large clusters of lymphoid tissue known as MALT (Mucosal-associated Lymphoid Tissue).
    • GI Muscularis Mucosa: A thin muscular layer composed of smooth muscle cells that actuates local motions of the GI mucosa.
  • GI Submucosa:
    • A wide layer of collagenous tissue that contains vasculature and nerves that support and modulate the mucosa. The nerve fibers within the submucosa form a dense network known as the Submucosal Plexus which mostly regulates GI secretion from the mucosa.
  • GI Muscularis Propria:
    • A large muscular layer whose inner fibers are arranged in a circular geometry while its outer fibers are arranged in a longitudinal geometry. This layer is largely responsible for bulk movement of food within GI tract and is controlled by a dense nervous network known as the Myenteric Plexus which is located between the circular and longitudinal fibers.
  • GI Adventitia:
    • A layer of collagenous tissue that conducts larger vasculature and nerves that support and modulate the entire GI tract.
GI Tract Segments