Mucopolysaccharide hyaluronic acid is present in which among the following:

Hyaluronic acid is a sulphate free mucopolysaccharide. It is present in vitreous humor of the eye. It is also present in skin, synol fluid, umbilical cord, hemolytic streptococci and in rheumatic nodule. It occurs both free and salt like combination with proteins and forms ground substance of the mesenchyme, an integral gel like ground substance of connective tissue and other tissues. It is composed of repeating units of N acetyl glucosamine and D glucuronic acid. Functions: It acts as a cementing substance and contribution to tissue barriers which permits metabolites to pass through but resist penetration by bacteria and other infective agents. In joints it acts as a lubricant and shock absorbent. Ref: Textbook of Medical Biochemistry By M. N. Chatterjea, page 38. Textbook of Biochemistry for Dental/Nursing/Pharmacy Students By Chatterjea page 15