Liver histology

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.These granules are considered a sign of “wear and tear” and it’s normal to see the amount of lipofuscin gradually increase with age.The hepatocyte plates have a supportive tissue or stroma of reticulin fibers.These fibers are difficult to see with an H&E stain, but a reticulin-specific stain can be used in order to visualize the fibers and hepatocyte plates better.A reticulin stain is actually used to help diagnose hepatocellular carcinoma, since a liver with plates that are more than 3 cells thick is diagnostic, which we can see in this image.##SummaryAlright, as a quick recap.The liver is organized into thousands of hepatic lobules.At lower magnification, the lobules can be identified by their prominent central vein, as well as a slightly pale central portion of the lobule compared to the edges of the lobules.The portal triads are found at the corners of the lobules.Each portal triad contains a portal venule, hepatic arteriole, and bile duct.The venule can be identified by its large lumen and thin wall.The arteriole will have a thicker wall, but a much smaller diameter.And the bile duct can be identified by its simple cuboidal epithelium.The hepatocytes are large polygonal cells with very eosinophilic cytoplasm and basophilic nuclei.The hepatocytes are organized into branching hepatocyte plates of cells that radiate out from the central vein.And lipofuscin is a sign of “wear and tear” seen within hepatocytes as fine brown granules.

recap. The liver is organized into thousands of hepatic, lobules at lower magnification.

The lobules can be identified by their prominent Central vein, as well as a slightly pale central portion of the lobule, compared to the edges of the LA people's the portal.

Triads are found at the corners of the lobules. Each portal.

Triad contains the portal venule. Hepatic arterial and bile duct.

The vanual can be identified by its large Lumen and thin wall, the arterial will have a thicker walls but a much smaller diameter and the bile duct can be identified by a simple cuboidal epithelium.

Parasites are large polygonal cells with very eosinophilic. Cytoplasm and basil.

Philip nuclei are organized into branching. Hepatocyte place of cells that radiate out from the central vein and lipofuscin is a sign of wear and tear seen within hepatocyte as fine.