Histology of Liver

Components

• Hepatocytes
• Connective Tissue
• Blood vessels, nerve, lymphatic vessels, bile ducts
• Sinusoidal capillaries

Classic lobule

• Central vein surrounded by hexagonal block of tissue
• hexagon defined by layer of connective tissue joining six portal triads

Portal lobule

• Triangle drawn between three central veins
• portal triad in centre as bile drains to bile duct

Liver acinus

• diamond shaped with two central veins at limits of long diagonal; portal triads at limits of short diagonal
• defines three zones
  • zone 1 - recieves blood first:
    • exposed to more oxygen and more toxins
  • zone 2 - intermediate zone
  • zone 3 - recives oxygen and toxins last

Sinusoids

• principal functional unit of liver
• lined with thin, discontinuous endothelium
  • large fenestrae, without diaphragms present in endothelial cells
  • large gaps present between neighbouring endothelial cells
  • basement lamina discontinuous
• lined by Kuppfer cells - part of mononuclear phagocyte system
  • may be involved in final breakdown of old red blood cells

Perisinusoidal space (Space of Disse)

• lies between hepatocytes and sinusoids
• microvilli extend into it from hepatocytes
• contents are not dissimilar to blood plasma
• hepatocytes secret protein and lipoprotein into space of Disse
• lipocytes (Ito Cells) often found in space of Disse                                     

Bile canaliculi

• formed between adjacent hepatocytes.
• sealed from rest of intercellular space by zonula occuldens
• drain into small bile canals (canals of Herring) and thence into bile duct of portal triad