Vitrification is a common method for
cryopreservation of gametes and embryos. Although
successful oocyte vitrification has been achieved in
several animal species, subsequent progress is still
limited especially in buffalo. To improve the
effectiveness of vitrification of buffalo oocytes, two
experiments were conducted. The first experiment
evaluated the effect of cryodevices on viability and
maturation of vitrified, matured buffalo oocytes. The in
vitro matured oocytes were divided into two groups, the
first was vitrified using conventional French straws,
while the other was vitrified using Cryotops. There was
a significant reduction in the morphologically normal
oocytes after vitrification with both methods.
Maturation rates of vitrified thawed buffalo oocytes
were significantly higher in Cryotops than straws. The
survival rate after vitrification was similar for both
straws and Cryotops. The percentages of viable oocytes
were significantly lower in straw than in controls. The
second experiment evaluated the effect of two
concentrations of cryoprotectants on the vitrification of
in vitro matured buffalo oocytes. Mixtures of DMSO
and EG as cryoprotectant (CPA) solutions were
prepared in TCM-199 with two concentrations of
cryoprotectants. The first concentration was 6 M V2 (3 M
E.G + 3 M DMSO), and the second concentration was 7 M
V2 (3.5 M DMSO + 3.5 M EG). Each concentration of
cryoprotectants was added in two steps, with the first
step having half the concentration of the second (and
final) concentration. The survival rate after vitrification
was similar for both concentration (6 M and 7 M)
groups. The maturation rates of vitrified thawed buffalo
oocytes were significantly higher in 7 M concentration
than in the 6 M group. In conclusion, the survivability
and meiotic competence of buffalo oocytes improved
with vitrification at higher concentration of
cryoprotectants and using cryotops. |
