Large, polygonal hepatocytes form the hepatic plate. Between the hepatic plates are the sinusoids. They differ from capillaries in that they are of greater diameter (9-12 micrometer), and their endothelial lining is atypical, with an incomplete basement membrane. The sinusoidal endothelial cell has a flattened nucleus and greatly attenuated cytoplasm. The endothelial lining appears incomplete, with gaps between adjacent cells and fenestrations in the attenuated cytoplasm. Kupffer cells are located among the endothelial cells, but they are often found within the lumen of the sinusoids. These cells are irregular, large, stellate in shape, and contain a large ovoid nucleus. The cytoplasm has many processes or pseudopodia and contains lysosomes and engulfed phagosomes. Kupffer cells are actively phagocytic, involved with the spleen in the removal of aged erythrocytes and other debris from the circulation.