Metastasis of a cancerous cell. Coloured scanning electron micrograph (SEM) of a tumour cell, showing pseudopodia protrusions (bottom left and right), a prominent feature of actively motile cells. The role of pseudopodia in metastasis (the spread of cancer cells around the body) is poorly understood but it appears that a protein, named autocrine motility factor (AMF), causes pseudopodia to extend prior to cell translocation. Locomotion is integral to the entire process of metastasis.

Credit: SUSAN ARNOLD/NATIONAL CANCER INSTITUTE/SCIENCE PHOTO LIBRARY

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T lymphocytes and cancer cell. Coloured scanning electron micrograph (SEM) of T lymphocyte cells (red) attached to a cancer cell. T lymphocytes are a type of white blood cell that recognise a specific site (antigen) on the surface of cancer cells or pathogens and bind to it. Some T lymphocytes then signal for other immune system cells to eliminate the cell. The genetic changes that cause a cell to become cancerous lead to the presentation of tumour antigens on the cell’s surface. Magnification: x2300 when printed at 10 centimetres wide.

Credit: STEVE GSCHMEISSNER/SCIENCE PHOTO LIBRARY

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Migrating cancer cells. Coloured scanning electron micrograph (SEM) of migrating, or metastasising, cancer cells. Only the nuclei (large, round) and the actin cytoskeleton (threads) can be seen. The other cell constituents have been removed. The cytoskeleton allows for directional movement of the cells. The movement of cancer cells around the body (metastasis) is an important part of a cancer’s malignancy. Magnification: x2650 when printed at 10 centimetres wide.

Credit: STEVE GSCHMEISSNER/SCIENCE PHOTO LIBRARY

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Scanning electron micrograph (SEM) of apoptosis (programmed cell death). Human carcinoma cell.

Credit: DAVID M. PHILLIPS/SCIENCE PHOTO LIBRARY

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Bone cancer cell. Coloured scanning electron micrograph of an osteosarcoma cancer cell. Osteosarcoma is an aggressive malignant neoplasm arising from primitive transformed mesenchymal cells. It is the most common histological form of primary bone cancer. Magnification: x3300 when printed at 10 centimetres wide.

Credit: STEVE GSCHMEISSNER/SCIENCE PHOTO LIBRARY

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Migrating breast cancer cell. Coloured scanning electron micrograph (SEM) of a cultured breast cancer cell (orange) moving (metastasising) through two holes in a support film. Numerous fillipodia (thread-like) and surface blebs (lumps) can be seen. These features are characteristic of highly mobile cells, and enable cancerous cells to spread rapidly around the body, and invade other organs and tissues (metastasis). The cells may clump to form tumours. Breast cancer is the most common form of cancer in women. Magnification: x5000 when printed 10 centimetres wide.

Credit: STEVE GSCHMEISSNER/SCIENCE PHOTO LIBRARY

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Dividing liver cancer cell. Coloured scanning electron micrograph (SEM) of a hepatocellular carcinoma (HCC) cell undergoing mitosis (nuclear division) and splitting into two daughter cells (left and right). Hepatocellular carcinoma is the most common type of liver cancer. It tends to occur in livers damaged by genetic defects, alcohol abuse, or chronic infection with diseases such as hepatitis B and C. Primary liver cancer, which starts in the liver, is relatively rare in the UK, with about 3,600 people diagnosed each year. However, because of the prevalence of hepatitis caused by contagious viruses, it accounts for up to half of all cancers in some undeveloped countries. Magnification: x3300 when printed at 10 centimetres wide.

Credit: STEVE GSCHMEISSNER/SCIENCE PHOTO LIBRARY

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Colorectal cancer cell. Coloured scanning electron micrograph (SEM) of a cancer cell from the human colon (large intestine). Cancer of the colon is also known as colorectal cancer. Symptoms include rectal bleeding and abdominal pain. Treatment is with surgery to remove the affected area. Colon cancer is one of the most common cancers in the Western world. Magnification: x4,000 when printed 10 centimetres wide.

Credit: STEVE GSCHMEISSNER/SCIENCE PHOTO LIBRARY

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Cancer cell culture, coloured scanning electron micrograph (SEM). The cancer cells have been grown on a support with holes, allowing them to show their ability to migrate (metastasise). This is the process by which cancer spreads in the body. Magnification: x2000 when printed at 10 centimetres wide.

Credit: STEVE GSCHMEISSNER/SCIENCE PHOTO LIBRARY

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Malignant cancer cell spreading into normal cells.

Credit: OMIKRON/SCIENCE PHOTO LIBRARY