Lactose and lactic acid crystals, LM

Light micrograph (LM) of Lactose and lactic acid crystals. Lactose is a disaccharide consisting of two subunits, a galactose and a glucose linked together. In young mammals, an enzyme called lactase is secreted by the intestinal villi, and this enzyme cleaves the molecule into its two subunits for absorption. Normally, as the young grow up, production of lactase gradually ceases, and they are then unable to metabolize lactose. Lactic acid is a chemical compound that plays a role in several biochemical processes. It is the acid that gives old milk its sour taste, and it accumulates in skeletal muscles during extensive anaerobic exercise, causing temporary muscle pain. Lactic acid bacteria also operate in the mouth, and the resulting lactic acid is responsible for the tooth decay known as caries. Magnification: x40 when shortest axis printed at 25 millimetres.