Development of Cat Embryos Produced by Intracytoplasmic Injection of Spermatozoa Stored in Alcohol

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.