Effect of storage of domestic cat (Felis catus) epididymides at 5°C on sperm quality and cryopreservation

Abstract 

Postmortem sperm recovery from the epididymides may constitute a powerful tool for the conservation of valuable genetic material. The domestic cat (Felis catus) is a good model for wild felids and, using this model, we have explored the effect of epididymides storage time on sperm motility and percentage of intact acrosomes upon sperm recovery and after cryopreservation. We also examined the effect of time of sperm equilibration with glycerol before freezing on sperm motility and the percentage of intact acrosomes. Motility varied between sperm recovered from epididymides that were stored for different times. Significant differences were seen in the sperm motility index (SMI) before freezing (55.91±2.02, 48.21±1.47, and 43.03±1.32) and after thawing (51.81±3.02, 41.90±2.14, and 42.35±1.95) of sperm recovered from epididymides stored for 0, 48, or 72h, respectively. The percentage of intact acrosomes did not vary significantly with storage time (average 60.33±1.38% before and 52.50±1.91% after freezing, respectively). The percentage of normal sperm after different storage times did not differ (average 19.22±1.25% normal sperm after recovery). When epididymides were stored for 72h, time of sperm equilibration with glycerol (30 vs. 120min) resulted in significant differences in both motility (SMI=39.17±2.76 and 45.00±2.65, respectively) and the percentage of intact acrosomes (45.76±4.91% and 60.67±3.64%, respectively) after thawing. In conclusion, best results are achieved when sperm are recovered from epididymides within 24h of cool storage and when they are equilibrated with glycerol during 120min before freezing. The current results should be useful in the further development of techniques for the rescue and cryostorage of epididymal spermatozoa of endangered felids.

Keywords: Cryopreservation, Domestic cat, Epididymides, Glycerol, Spermatozoa