When viewed under a microscope, the liver is seen as large network of units called hepatic lobules. The hepatic lobule is very small and looks like a six-sided cylinder.
The lobule itself is surrounded by connective tissue and has 5 to 7 clusters of vessels around its edges. These vessels include a branch of the portal vein, a branch of the hepatic artery, and a bile duct.
A central vein runs through the middle of the lobe and is surrounded by cords of liver cells that radiate out in all directions. Between these cords are wide thinwalled blood vessels called sinusoids. All of the blood drains into a hepatic vein which then circulates throughout the body.