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

Abstract

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°C 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°C 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 MII 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 COCsconditioned medium supplementation significantly increased nuclear maturation of canine oocytes.

Beneficial Effects of L-Carnitine Supplementation during IVM of Canine Oocytes on Their Nuclear Maturation and Development In Vitro

“…However, in the study of Songsasen et al [ 15 ], the collection of oocytes from large (>2 mm) follicles resulted in comparable maturation rates (37.7%) to our 0.3 and 0.6 mg/mL LC groups. The maturation rate reported in the 0.6 mg/mL LC supplemented group was also higher than those demonstrated previously when dog oocytes cultured in vitro for 72 h (0.0% to 6.82% [ 1 ], 25.5% [ 4 ], 2.48% to 13.23% [ 43 ], 5.56% to 21.82% [ 44 ], and 3.8% [ 45 ]). Our findings suggest that LC could positively impact oocyte maturation during a prolonged culture period [ 25 , 46 ].…”

“…COCs were then placed in 35-mm Petri dishes containing HEPES-buffered TCM-199 (H-TCM 199) and examined under a stereomicroscope. After three washes in the same medium, COCs with homogeneous dark cytoplasm and three or more layers of compact cumulus cells were chosen for IVM [ 1 , 4 ].…”

“…Assisted reproductive technologies (ARTs) are required in dog breeding programs to enhance domestic dog reproduction and serve as a model for the conservation of wild and endangered canid species. However, the development of ARTs, for example, in vitro maturation of oocytes (IVM), in vitro fertilization (IVF), and embryo culture, has lagged in dogs compared to other domestic species [ 1 ]. Failure to develop ARTs in canids results from peculiar species-specific reproductive characteristics of dogs [ 1 ].…”

“…However, the development of ARTs, for example, in vitro maturation of oocytes (IVM), in vitro fertilization (IVF), and embryo culture, has lagged in dogs compared to other domestic species [ 1 ]. Failure to develop ARTs in canids results from peculiar species-specific reproductive characteristics of dogs [ 1 ]. Dogs are a nonseasonal and monoestrous species, and they ovulate only once or twice a year at an interval of 5–12 months [ 2 ].…”

Assisted reproductive techniques for canines: preservation of genetic material in domestic dogs

“…Due to the lack of an efficient in vitro maturation method [ 106 , 107 , 108 , 109 ], there is limited possibility of embryo development after immature oocyte cryopreservation. However, the possibility of preservation of the viability of stored oocytes has been examined [ 110 , 111 ], in addition to oocyte ultrastructure, meiosis resumption, and gene expression in oocytes [ 112 ], primarily as preliminary studies on the cryopreservation of embryos [ 110 , 111 ].…”