Isolation and characterization of human and rabbit sperm tail fibrous sheath

Using mechanical and chemical dissection methods, fibrous sheath wasisolated both from normal ejaculated human spermatozoa and from rabbitcauda epididymal spermatozoa. The same techniques did not produce a purepreparation of fibrous sheath from ejaculated rabbit spermatozoa,suggesting that further cross-linking and stabilization of sperm structuresoccurs in response to components of the seminal plasma. The isolationprocedures were monitored by phase contrast microscopy and the purity ofthe fibrous sheath was verified by electron microscopy. Sodium dodecylsulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of isolated humanfibrous sheath revealed at least 14 protein bands of which the mostintensely stained were of molecular weight 84, 72, 66.2, 57, 32 and 28.5kDa. The rabbit fibrous sheath revealed at least 10 protein bands, of whichthe most intensely stained were 35.2, 32.7 and 28.5 kDa. The amino acidcomposition of the purified fibrous sheath from human and rabbitspermatozoa was similar, being high in aspartic acid and/or asparagine andglutamic acid and/or glutamine, serine, alanine, leucine, lysine andglycine, but low in histidine, tyrosine and isoleucine. This composition issimilar to that reported for the rat and suggests that mammalian sperm tailfibrous sheaths are composed of similar types of proteins, although thereare apparent differences in protein components between species.