Image: partial view of the liver of a rat. Stained with Masson's trichrome.
Hepatic lobule: (delimited by black asterisks) it is the functional unit of the liver. Hepatic lobules are limited by a layer of connective tissue that encloses numerous hepatocytes. Portal veins bringing blood from the intestine, arteries, and bile ducts that transport the bile synthesized by hepatocytes toward the gall bladder, run through this outer connective tissue layer. Blood flows toward the center of the lobule through anastomosed capillaries that lead to the central vein.
Portal areas: (delimited by blue asterisks) they are regions of the outer connective tissue layer found at the vertices of the hepatic lobules. Portal areas contain a vein, an artery and a bile duct, altogether known as portal triad.
Central vein: it is the blood vessel found in the center of the lobule. Sinousoids lead the blood with the metabolized substances by the hepatocytes into the central vein.
Sinusoids: they are the capillaries that run among the hepatocytes. Sinusoids are loaded with molecules released by the hepatocytes, as well as substances uptaked in the intestine during digestion. The blood stream of sinusoids is from the portal areas to the central vein. Sinusoid endothelial cells are discontinuous, i.e., there are gaps between adjacent endothelial cells, and it favors the exchange of molecules between the capillaries and the hepatocytes.
Dile duct: it is a duct that gathers the bile from the bile canaliculi. Bile ducts lead to the hepatic duct, which ends in the gall bladder. Bile is synthesized by the hepatocytes.
Portal blood vessels: there are arteries and veins at the portal areas, known as portal arteries and portal veins, respectively. Portal veins bring the substances from the intestine, and portal arteries supply oxygenated blood.