|General Gross Description|
The liver is the largest organ in the body, weighing 1.2 to 1.8 kg in the adult.
It occupies the entire right upper quadrant of the abdomen, extending into the left upper quadrant, in line with the nipple.
In an anterior view, it is a roughly triangular shaped organ and is covered by a smooth glistening capsule.
The color is uniformly dark red to maroon, with no little to no variation in color.
The gallbladder is attached to the inferior surface and can be visible from the anterior view along the lower border.
The liver is divided into the right lobe and left lobes.
The right lobe is significantly larger than the left lobe.
The liver is composed of lobules attached to each other by a scanty amount of connective tissue.
The connective tissue septa between the lobules hold branches of the hepatic artery and the portal vein, as well as bile ducts.
Each lobule of the liver is a spherical structure, a few millimeters in diameter.
The outline of these lobules is extremely irregular in man, but is clearly demarcated and polygonal in pigs.
|General Microscopic Description|
Microscopically, the liver is composed primarily of hepatocytes which are arranged in cords that extend from the central vein to the portal triads.
Each hepatocyte is a polygonal cell with a large, centrally located nucleus.
The cytoplasm is faintly granular and distinctly acidophilic (pink).
The nucleus has a faint chromatin structure with a distinct nucleolus.
In healthy liver cells, one can often see a central bluish staining deposit of glycogen in the nucleus.
The glycogen is not within the nucleus, but is cytoplasmic and pushes into the nucleus.
Adjacent liver cells form tight junctions.
This surface contains a bile cannaliculus.
In humans, the lobular demarcations are not as distinct as in the pig
Each liver lobule is surrounded by a number of portal triads, each consisting of a single branch of the portal vein, a branch of the hepatic artery, and a bile duct.
The liver cell cords are separated from each other by sinusoids which contain blood.
The blood is separated from the liver cells by endothelial cells.
Numerous Kupfer cells, which are macrophages by lineage, are also present along the sinusoidal space.
The liver cells themselves are separated from the sinusoid by a narrow space called the space of Disse.
In a normal liver, very little connective tissue or inflammatory cells can be seen except for a few lymphocytes in the portal tracts.
Fawcett DW. Bloom and Fawcett a textbook of histology. 12th ed. New York: Chapman & Hall, 1994, pp 652 et seq.
Gray H. Gray's Anatomy, 15th Edition. New York: Barnes & Noble, Books, 1995, 916 et seq.
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||Synopsis by: T.V.Rajan, M.D., Ph.D. (T56000M00100)