1. Average values for the total carbohydrate content of human and bovine platelets were 8.47 and 8.77 per cent of the dry weight, respectively. On a dry weight basis, human platelets were calculated to be approximately one-third larger than bovine platelets. By chemical and chromatographic analysis, glucose, galactose, mannose, fucose, ribose, glucosamine, galactosamine, glucuronic acid and sialic acid were detected in both human and bovine platelets.
2. Glucose and ribose were found to be the only monomers present in the 5 per cent TCA-soluble fractions of both human and bovine platelets. The TCA-insoluble residue contained glucose, galactose, mannose, fucose, ribose, glucuronic acid, glucosamine, galactosamine and sialic acid. The acid mucopolysaccharide fraction of both human and bovine platelets contained galactosamine and glucuronic acid monomers as well as galactose, glucose, and ribose.
3. Glycogen was found in both human and bovine platelets. Total glycogen was extracted by 5 per cent TCA from sonorated human and bovine p1atelets; however, subsequent ethanol precipitation of tile glycogen was incomplete. In contrast, 30 per cent KOH extraction followed by ethanol precipitation resulted in complete recoveries of the glycogen.
4. Variations ill both total hexose and glycogen contents were found in both human and bovine platelets. These variations were partially dependent on the length of storage of the platelets in whole blood or in 0.85 per cent NaCl after separation from whole blood.