Full Length Research Paper

Retinoic acid effects on nuclear maturation of bovine oocytes in vitro

Vahid Vahedi*, Saeed Zeinoaldini, Hamid Kohram and Abbas Farahavar

Department of Animal Science, Faculty of Agriculture and Natural Resources, University of Tehran, Karaj, Iran.

*Corresponding author. E-mail: vahedi_tikme@yahoo.com. Tel: +98-261-2248082. Fax: +98-261-2246752.

Accepted 8 December, 2008

In the present study, the effect of all-trans retinoic acid (t-RA) administration during in vitro maturation (IVM) on bovine oocytes maturation was determined. Concentrations of t-RA (RA; 0, 0.25, 0.5 and 1 µM) and 0.1% ethanol (vehicle) were included in the maturation medium. Ovaries collected from the local abattoir were transported to the laboratory in in 0.9% NaCl with 100 IU/ml penicillin and 100 μg/ml streptomycin at 30 - 35°C within 1-2 h after collection. The oocytes of antral follicles, 2 to 8 mm in diameter, were recovered by aspiration. After preliminary evaluation, the oocytes were selected and washed four times in HEPES-TCM 199 supplemented with 2% FBS, 0.2 mM sodium pyruvate, 100 IU/ml penicillin and 100 μg/ml streptomycin. Then 10 cumulus-oocyte complexes (COCs) were subjected to each droplet of maturation medium and incubated at 38.5°C, 5% CO₂ and 95% humidity for 24 h. Maturation medium was bicarbonate-buffered TCM199 supplemented with 10% FBS, 0.2 mM sodium pyruvate, 5 µg/ml bovine FSH, 0.01 IU/ml bovine LH, 100 IU/ml penicillin and 100 μg/ml streptomycin. Results show different concentrations of t-RA have no effect on cumulus expansion. The rate of oocytes developing to the MII stage compared to control, vehicle, and 0.25 µM groups was significantly increased with 1 µM t-RA treatment (p<0.05). In conclusion, 1 µM retinoic acid significantly increased the bovine oocyte maturation in the commercial TCM199 medium.

Key words: in vitro maturation, retinoic acid, bovine oocytes.