Heart ventricle. Coloured scanning electron micrograph (SEM) of a fracture through a heart to show the interior of the ventricle. Erythrocytes (red blood cells) are seen within the ventricle. The ventricles are the lower chambers of the heart. The right ventricle receives deoxygenated blood from the body and pumps it through the pulmonary artery to the lungs. The left ventricle receives oxygenated blood from the lungs and pumps it through the main artery, the aorta, to the rest of the body. Magnification: x500 when printed 10 centimetres wide.