Effect of bovine cumulus-oocyte complexes-conditioned medium on in-vitro maturation of canine oocytes

摘要

Purpose To investigate the ability of medium conditioned with bovine cumulus-oocyte complexes (COCs) to support nuclear maturation of canine oocytes recovered from domestic dog ovaries.Methods Cumulus-oocyte complexes were obtained from ovaries of domestic bitches (8 months old to 7 years old), and in-vitro maturation was evaluated in TCM-199 supplemented with different concentrations (0, 20, 30 or 50%) of bovine COCs-conditioned medium (BCM). The canine COCs were cultured for 72 or 96 h at 38.5癈 in 5% CO_2, 5% O_2 and 90% N_2. The bovine COCs-conditioned medium was obtained from culture of bovine COCs with TCM-199 supplemented with 5% FCS for 22 h at 38.5癈 in 2% CO_2, 98% air.Results The proportion of germinal vesicle breakdown (GVBD) after 72 h was significantly higher (P < 0.05) in medium supplemented with 30% BCM (20.7%) compared with the control group (13.4%). The rates of GVBD-MII stage were significantly higher (P < 0.05) when oocytes were matured with BCM at concentration of 30% (41.5%) compared with control (26.6%) after 72 h in-vitro culture. After 96 h in-vitro culture, the oocytes matured in medium supplemented with 30% BCM (5.5%) showed a significant increase (P < 0.05) in the proportion of Mil compared with control (0.7%). However, increasing the cultivation time from 72 to 96 h resulted in an increase in oocyte degeneration rate.Conclusions The results suggested that bovine COCs-conditioned medium supplementation significantly increased nuclear maturation of canine oocytes.