Capacitation of rabbit spermatozoa in vitro

Abstract

This research was carried out to define in vitro conditions that would enable ejaculated rabbit sperm to fertilize ova in vitro. During 20 min exposure of sperm cells to defined media of increasing NaCl concentrations, progressive removal or alteration of sperm surface seminal plasma antigenic components was initiated and completed as reflected by an immunological assay at approximately 300 and 380 mOsm/kg, respectively. Hypertonic (380 mOsm/kg) medium effected complete removal or alteration of these components as determined by the immunologic assay during the first 5 min of sperm treatment. Isotonic (305 mOsm/kg) treatment was shown to have effected removal or alteration of some but not all of the antigenic sperm coating seminal plasma components detectable by this means during 20 min of exposure. One hundred and seventy six 2 and 4 cell stage embryos were transferred to 14 recipient does. Twenty four embryos (13.1%) were implanted in 6 recipients but most were resorbed. Three embryos resulting from in vitro fertilization with in vitro capacitated ejaculated rabbit sperm were carried successfully to term by 2 recipients and 2 of the offspring were males. This provides documentation for the authenticity of in vitro capacitation of ejaculated sperm of a mammalian species and represents the initial successful combination of in vitro sperm capacitation with in vitro fertilization and embryo transfer in the rabbit.