Liver histology

Transcript

The liver is the largest internal organ in the body and weighs about 1.5 kg.

It’s surrounded by a capsule of fibrous connective tissue called Glisson’s capsule.

If we look at the liver from an inferior view, which is a view from the bottom of the liver, we can see that the liver is divided into a large left lobe and right lobe, as well as two smaller lobes, called the quadrate and caudate lobes.

The liver parenchyma or functional tissue of the liver is organized into thousands of hepatic lobules, which have a dual blood supply that comes from terminal branches of the hepatic portal vein and hepatic artery.

The blood then flows through sinusoids surrounded by hepatocytes before draining into the lobule’s central vein.

Hepatocytes are the main functional cells of the liver that perform a large variety of functions, including the production of bile, a number of plasma proteins, and non-essential amino acids; the metabolism of fat, carbohydrate, and protein; the storage of glucose, vitamins, and iron; and the breakdown or detoxification of metabolic waste products, drugs, and toxins.

At lower magnification, the hexagonal shape of the hepatic lobules can be identified by their slightly darker edges and the prominent central veins in the center of each lobule.

The portal triad consists of a bile ductule, portal venule, and arteriole.

After identifying the lobule, it can be easier to locate portal triads in an image since they’re typically located at the corners of the lobules.

If we take a closer look at just one portal triad, we can more easily identify the portal venule by its large diameter and thin walls compared to the arteriole, which has a much smaller diameter and thicker walls.

Similar to this image, the portal tract can sometimes have more than one bile duct.

The bile ducts can be identified by their prominent simple cuboidal epithelium.

Also in this image are a couple small lymphatic vessels, which have even thinner walls than the venule.

Let’s now take a closer look at the hepatocytes, which are large polygonal epithelial cells that form branching plates that are only one-cell thick, separated by sinusoids, and radiate outward from the central vein.

The sinusoids carry blood from the hepatic arteriole and portal venule to the central vein, while the bile canaliculi or capillaries carry the bile produced by hepatocytes in the opposite direction in order to drain into the bile ductules.

The hepatocyte’s cytoplasm is very eosinophilic, or pink because they contain a lot of mitochondria.

Many of the cells in this image also have fine brown granules within the hepatocytes called lipofuscin.