Spread of cancer cells. Animation showing the cellular basis of the process of metastasis, the spread of cancer from a primary to a secondary site. This occurs in four stages, shown here. (I) The normal state is shown with labels for epithelial tissue (white, top), the basal lamina (below epithelial tissue), connective tissue fibres (green), capillaries (red), white blood cells (yellow, rounded) and fibroblasts (yellow, pointed). (II) The cancer cells appear when some cells undergo uncontrolled cell divisions (pink) and accumulate and exert a pressure against the basal lamina. (III) The pressure grows and breaks the basal lamina. (IV) The cancer cells then progressively invade the underlying connective tissue and migrate into blood vessels and are carried around the body and can form secondary cancers at other locations. For this animation with labels, see K004/3397. |