Microinsemination of rabbit oocytes with heat-treated sperm: embryonic development

A study was conducted to evaluate the ability of rabbit oocyte to develop to the pronuclear stage and subsequent development if injected with heat-treated sperm. The rate of fertilization of eggs after microinjection of cauda epididymal spermatozoa heated at 60 degrees C for 30 min was 36%; the rate of cleavage was 24%. The rate of fertilization after microinjection of heat-treated sperm nuclei was 43%; the rate of cleavage was 26%. On the other hand, the rate of fertilization of eggs injected with sperm without heat treatment was 43%, the rate of cleavage was 29%, and there was no difference between eggs microinjected with heat-treated spermatozoa or sperm nuclei and those not heat treated. Of the viable eggs injected with heat-treated sperm, 16% developed to the 6- to 8-cell stage 72 h after injection.