Caption

Goblet cells. Coloured transmission electron micrograph (TEM) of a section through goblet cells in the lining of the small intestine, part of the digestive tract. They are full of mucus (yellow). A goblet cell secretes the mucus to protect the lining of the intestine. The brush-like surface of the small intestine consists of microvilli (red) which increase the surface area available for absorption of nutrients such as lipids, proteins and fat-soluble vitamins. The microvilli have a rapid turnover of 3-4 days. Magnification: x5500 when printed 10 centimetres wide.