Fucosylation Events during Mammalian Spermatogenesis ab

Surface glycoproteins are involved in many aspects of cellular differentiation and interaction.Biological systems employing membrane glycoconjugates as determinants of cellular recognition processes include myogenesis,' retinal development,2 and hematop~iesis.~Interactive events at the level of individual cells also employ surface glycocongugate mediators, as exemplified by slime mold associations: cancer metastasis,' and cellular pinocytosis.6Because spermatogenesis in mammals entails highly orchestrated cellular interactions, similar in many respects to those cited above, it is probable that specific alterations in plasma membrane glycoproteins and glycolipids play important regulatory functions during the differentiation of the spermatozoon.Current evidence, in fact, demonstrates that a variety of changes in germ-cell surface carbohydrate moieties do occur.Furthermore, in many instances these alterations occur sequentially and exhibit restricted temporal distributions during spermatogenesis.Cells early in meiotic prophase express surface antigenic determinants recognized by monoclonal antibodies specific for high molecular weight glycoc~njugates.~In addition, these particular antigenic determinants are progressively masked by the addition of sialic acid residues on germ-cell surfaces as Funding for these experiments was provided by Grants to C.F.