Reproduction, Fertility and Development Reproduction, Fertility and Development Society
Vertebrate reproductive science and technology


K. Miyata A , H. Koyama A , C. Lessard B , J. Singh C and O. Dochi A

A Department of Dairy Science, Rakuno Gakuen University, Ebetsu, Hokkaido, Japan;

B Agriculture and Agri-Food Canada, Saskatoon, Saskatchewan, Canada;

C Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada

Reproduction, Fertility and Development 22(1) 331-331
Published: 8 December 2009


Follicular fluid from small and large bovine follicles contains large amounts of progesterone, and during preovulatory period progesterone concen- tration increase markedly by 18 h after LH surge. Furthermore, cumulus cells express membrane progestin receptor beta (Liu et al. 2008 Steroids 73, 1416-1423). For these reasons, we hypothesized that progesterone supports maturation of preovulatory bovine oocytes to MII stage. The object of this study was to investigate the effect of progesterone supplementation of in vitro maturation medium on competence of bovine oocyte to develop into blas- tocysts in vitro. COCs were collected by the aspiration of 2-6 mm follicles from ovaries within 6 h of slaughter. The COCs were divided into 5 groups: (1) a control group, TCM-199 supplemented with 5% calf serum (CS) as IVM medium, and (2 to 5) progesterone (P4) supplementation groups, TCM- 199 supplemented with 5% CS and 1, 3, 5, and 10 μg mL-1 of P4. Groups of 10 COCs were incubated in 50-μL drops of IVM media at 38.5°C under an atmosphere of 5% CO2 in air for 20 h. The matured COCs were inseminated with 3 × 106 sperm mL-1. After 18 h of gamete co-culture, the pre- sumptive zygotes were cultured in CR1aa media supplemented with 5% CS for 9 days at 38.5°C under an atmosphere of 5% CO2, 5%O2, and 90% N2. Embryonic development was evaluated at 48 h after IVF (total cleavage rates) and on Days 7 to 9 (blastocyst rate). Data was analyzedby chi-square test. The results are presented in Table 1. There were no significant differences in the cleavage rates between treatments. However, the blastocyst formation rate of 5 μg mL-1 P4 supplementation group was significantly higher than that of 10 μg mL-1 P4 supplementation group (P < 0.05). In addition, the blastocyst formation rates of 10 μg mL-1 P4 supplementation group was lower than the other groups. These results suggest that progesterone supple- mentation of in vitro, maturation medium affects the competence of the oocytes to develop into blastocysts in vitro, and 5 μg mL-1 P4 supplementation may be effective in increasing embryo production. Furthermore, 10 μg mL-1 P4 supplementation has negative effect on the oocyte competence.

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