Development of cat embryos produced by intracytoplasmic injection of spermatozoa stored in alcohol

Contents This study was conducted to examine whether cat spermatozoa stored in ethanol for 1 month was capable of developing into pronuclei and of supporting normal embryonic development. In vitro matured oocytes were injected with frozen–thawed spermatozoa and ethanol‐stored spermatozoa. The status of oocytes and sperm nuclei was examined at 4 and 18 h after injection of spermatozoa, and the presumptive zygotes were cultured for 7 days to assess the development of oocytes injected with each storage sperm. The percentage of enlarged sperm head at 4 h after injection was higher in ethanol‐stored spermatozoa than in frozen–thawed spermatozoa, but there was no significant difference in the development of oocytes and sperm nuclei at 18 h after injection between the two groups. The development of oocytes to the blastocyst stage after injection of spermatozoa was observed only in oocytes with frozen–thawed spermatozoa. Of oocytes injected with ethanol‐stored spermatozoa, two (2.8%) oocytes developed to the 16‐cell stage. These results indicate that cat spermatozoa stored in ethanol can decondense and form male pronuclei after intracytoplasmic injection. However, the oocytes injected with ethanol‐stored spermatozoa did not have the ability to develop to the blastocyst stage.