Effects of preservation of mouse spermatozoa in electrolyte-free solution at 4 degrees C on the outcome of mouse in vitro fertilization

Purpose: The aim was to assess the fertilizing capacity of spermatozoa cool -preserved in electrolyte-free (EF) solution. Methods: Mouse spermatozoa were cool-preserved in EF solution and the acros omal status of the spermatozoa was compared before and after preservation u sing chlortetracycline stain. Mouse oocytes were inseminated by spermatozoa cool-preserved in EF solution for 2, 4, or 7 days and fertilization and bl astocyst rates were evaluated. Results: Acrosomal status of spermatozoa cool-preserved in EF solution was not different from spermatozoa before preservation, but the capacitated and acrosome-reacted spermatozoa significantly increased after reinitiation. C ool-preservation in EF solution for up to 4 days did not affect fertilizati on rate. Blastocyst rate of embryos derived from spermatozoa cool-preserved for 4 or 7 days in EF solution was significantly lower than that of embryo s derived from fresh spermatozoa. Conclusions: Mouse spermatozoa cool-preserved in EF solution possesses as m uch fertilizing capacity as fresh spermatozoa. However prolonged preservati on affects the embryonic development.