Thyroid cancer cell. Coloured transmission electron micrograph (TEM) of a thyroid cancer cell. The nucleus (brown) contains chromatin, a complex of DNA (deoxyribonucleic acid) and proteins. The nucleus is abnormally large, this is common in cancer cells as they are abnormally active. The cell is also spherical, another characteristic of cancer cells. The thyroid gland is located at the base of the neck and produces hormones that regulate the metabolism. Thyroid cancer is more common in women than men. It can cause swelling and hoarseness. Treatment is with surgical removal of the thyroid, often combined with radioactive iodine therapy. Magnification: x4000 at 10 centimetres wide.