Liver blood vessels. Coloured scanning electron micrograph (SEM) of a resin cast of blood vessels in liver tissue. The intricate bunches branching off the main vessels correspond to liver lobules. This network of vessels infiltrates the tissue, supplying it with blood. Gases and nutrients are exchanged between the blood and surrounding tissue through the permeable walls of capillaries, the smallest blood vessels. The liver's functions include detoxifying waste from the blood, and the storage and metabolism of fats. The cast was made by injecting resin into the blood vessels. The surrounding tissues were then chemically digested. Magnification: x88 at 6x7cm size.