Effect of cumulus cells on canine oocyte vitrification using DAP213 cryotop method

Abstract EN

The present study investigated the influence of cumulus cells on vitrification of canine germinal vesicle stage oocytes, and assessed the ability of vitrified –warmed oocytes for further maturation in vitro.

Selected cumulus-oocyte complexes (COCs) or cumulus-free oocytes or partially denuded were vitrified in DAP 213 solution.

The vitrified-warmed oocytes were observed morphologically, and the plasma integrity was assessed.

The viable oocytes in each group were cultured in TCM-199 for 72 h at 38.5 °C in 5% CO2, 5% O2 and 90% N2.

All media were supplemented with 10% of FCS, 50 ng/mL of EGF, 2 μg/mL of estradiol-17β, 0.1 IU/mL of hCG, 0.1 IU/mL of FSH, 0.25 mM of pyruvic acid, 100 μM of β-mercaptoethanol, and antibiotics.

The viability of vitrified-warmed intact oocytes (52.8%) was higher than denuded oocytes (33.9%, P < 0.05), however, there is no differences between the partially denuded oocytes (43.9%) and denuded oocytes (33.9%, P > 0.05).

The highest percentage of M-II oocytes (P < 0.05) was observed in the intact group (3.1%) compared to the denuded group (0.8%).

When compared to the denuded group (2.3%), an increase (P < 0.05) in the proportions of M-I oocytes was observed in the intact group (8.3%) and partially denuded group (5.5%).

The overall meiotic resumption was greater (P < 0.05) in the intact and partially denuded groups than in denuded group.

In conclusion, the contact of cumulus cells with canine oocytes improved the viability after vitrification and enhanced the meiotic resumption of oocytes after in vitro maturation.