OUTER DENSE FIBERS OF HUMAN SPERMATOZOA - PARTIAL CHARACTERIZATION AND POSSIBLE PHYSIOLOGICAL FUNCTIONS

The outer dense fibres are accessory fibres in the spermatozoon. They represent up to 30% of the protein portion in human spermatozoa and ar e involved in sperm progressive motility. If outer dense fibres are mi ssing or developed poorly, spermatozoa are only locally motile. For is olation of the outer dense fibres, human spermatozoa were sonicated at 25 kHz and the flagella were separated by density gradient centrifuga tion in Percoll. Thereafter, membranes and fibrous sheath were dissolv ed under reducing conditions in the cationic detergent cetyltrimethyla mmonium bromide for 30, 60 and 90 min, respectively. The isolation ste ps were monitored by phase contrast microscopy and electron microscopy . After SDS-polyacrylamide gel electrophoresis and silver staining of isolated outer dense fibres, two protein bands at 55 and 67 kDa. could be detected. By means of rhodamine B staining, no phosphorus could be detected in the outer dense fire proteins.