MHS 206 Liver

Liver

The classic liver lobule in pigs and many other species (but not human) is surrounded by a thin capsule of connective tissue.

Lobules are roughly hexagonal with a central vein at its center and six portal triads at its periphery. (However, the random direction of a section makes this classical description rarely seen in a single profile.)

• Central Vein - large venule at the center of the lobule
• Hepatocytes - anastomosing plates, one cell thick, radiate outward from the central vein separated by sinusoidal capillaries and supported by reticular fibers
• Hepatic Stellate Cells (also known as Ito cells) - lipid-containing cells found in the walls of sinusoids. Their nuclei are irregularly shaped (often appear flattened) surrounded by multiple lipid droplets. These mesenchymal cells have a crucial role in liver injury, regeneration, and fibrosis.
  • Lipid droplets are clear because their contents are extracted during sample preparation
• Portal Triads - at the corners of each lobule
  • Hepatic Arterioles - supply oxygen-rich blood to sinusoids
  • Portal Venule - supply nutrient-rich blood from the gastrointestinal tract to sinusoids
  • Bile Ductules - drain bile from hepatocytes to the periphery
  • Lymphatic Vessels - drain lymph from perisinusoidal spaces of Disse to the periphery
• Bile Ducts (cross-section and longitudinal) - lined with a simple cuboidal epithelium.