Inhibition of fertilization <i>in vitro</i> by treatment of rabbit spermatozoa with univalent isoantibodies to rabbit sperm hyaluronidase

Abstract

Institute for Molecular and Cellular Evolution, University of Miami, Coral Gables, Florida33134, U.S.A. Isoantibodies to whole semen or epididymal spermatozoa of rabbits inhibit fertilization in vitro (Russo &amp; Metz, 1974a). This inhibition is attributed to a primary blocking of one or more sperm antigens essential for the sperm-egg interaction, and not to a secondary action (e.g. agglutination, complement-dependent immobilization), because univalent (Fab) antibody fragments, which do not agglutinate or immobilize spermatozoa, are also effective. Hyaluronidase, the sperm enzyme required for penetration of the cumulus surrounding the egg, could be one such sperm antigen. This possibility is supported by the fact that cumulus dispersion was inhibited in the experiments of Russo &amp; Metz (1974a) and that hyaluronidase-inhibiting antibodies are present in isoantisera to rabbit semen (Metz, Seiguer &amp; Castro, 1972). It is necessary to employ antibody preparations specific for rabbit sperm hyaluronidase to examine critically the inhibition of fertilization by antihyaluronidase