Table 1.

Definition and characteristics of hyaluronan (hyaluronic acid) and hylans

Definition	Characteristics
Hyaluronan (hyaluronic acid) or sodium hyaluronate	Long, nonsulfated, straight chains of variable length
	Repeating disaccharide unit of N-acetylglucosamine and glucuronic acid
	Forms a randomized coil in physiological solvents
	Average MW 4–5 million Da
Hylans	Crosslinked hyaluronan chains in which the carboxylic and N-acetyl groups are unaffected
	MW of Hylan A is 6 million Da
	Can be water-insoluble as a gel (e.g. hylan B) or membrane bound

MW, molecular weight.