Hyaluronic acid, molecular model. Hyaluronic acid (or hyaluronon) is a glycosaminoglycan, a type of biological polymer made up of repeating units of a disaccharide (two sugar molecules) formed of D- glucuronic acid and D-N-acetylglucosamine. It is widely distributed in connective tissues, joints and skin. It acts as a lubricant in joint spaces, and is a major component of cartilage and skin. Because of this it has found uses in medicines and cosmetics, as Healon for use in eye surgery and Restylane for wrinkle removal. Only a small part of the molecule is seen here; the polymer may be many thousands of units long. Atoms are colour- coded: carbon (yellow), oxygen (red), nitrogen (blue), hydrogen (white) and sodium ions (grey).