Sperm VS CO2.xlsx

Post-euthanasia
cryopreservation of epididymal sperm is a common method to preserve and
distribute valuable mouse models worldwide. However, the euthanasia method used
prior to sperm collection must not adversely affect sperm quality. The most
common method of euthanasia in mice is CO2 asphyxiation, but its effect on sperm quality is largely unknown. The objective of
this study was to determine the effects of CO2 euthanasia on C57BL/6
mouse sperm post-recoveries and following freezing and thawing. First, post-mortem sperm concentration, progressive motility, curvilineal
velocity (VCL), average path velocity (VAP), and progressive velocity (VSL) were
analyzed for mice euthanized via either
CD, high flow CO2 (100%), or low flow CO2 (30%)
displacement/minute, respectively. Then, in-vitro fertilization and embryonic
development rates were determined using frozen-thawed sperm from each euthanasia
method. There were no differences in sperm concentrations, progressive
motility, VAP or VCL for fresh or frozen-thawed sperm. Frozen-thawed sperm collected
from the CD group had higher VCL values compared to sperm collected from the
low flow group (P=0.039). There were no
differences in fresh sperm, or between sperm collected from the CD vs high flow
CO2 or high flow vs low flow CO2. There were no differences between groups for fertilization (P=0.452) and blastocyst development
rates (P=0.298) from using frozen-thawed
sperm collected between the groups. The results suggest that CO2 euthanasia method
can serve as an alternative to CD in the case of technical or personal reasons
to obtain optimal quality mouse sperm for cryopreservation and comply with the animal
and human welfare.