Images Dated 9th September 2002

False-colour SEM of human skin from a blister

False colour scanning electron micrograph of human skin from a blister on the palm of the hand (male). The skin on the palm is neatly arranged in ridges (not seen) with sweat pores (seen) appearing as miniature depressions tunnelling into the ridge- peaks. The external surface of skin, the epidermis, consists of keratinised, flattened layers of cells. Keratinization occurs when deposits of the fibrous protein keratin are layed down in the cells, causing them to toughen. This outer layer of cells is shed continuously (flaky) & is replaced by progressive movement & maturation of cells from the skin beneath. Magnification: X71 at 35mm size. Original is BW print P710/152

© DR JEREMY BURGESS/SCIENCE PHOTO LIBRARY

Pepsin molecule

Pepsin enzyme. Computer graphic of the protein- digesting enzyme pepsin. It is a protease enzyme that is secreted as part of gastric juice into the stomach in an inactive form known as pepsinogen. When it comes into contact with hydrochloric acid it is converted into the active form that hydrolyses proteins into smaller polypeptides (peptones). The molecule's backbone (red ribbon) and individual atoms (coloured dots) are seen

© DR TIM EVANS/SCIENCE PHOTO LIBRARY