Effect of fibroblast growth factor 2 (FGF2) and insulin transferrin selenium (ITS) on in vitro maturation, fertilization and embryo development in sheep

Abstract

The present study evaluated the effect of fibroblast growth factor 2 (FGF2) and insulin-transferrin-selenium (ITS) to the in vitro maturation and embryo culture media on ovine oocyte maturation, cleavage and embryo development. Oocytes having more than five layers of unexpanded cumulus cells and granular homogenous ooplasm were cultured into 50 μL droplets of eight different culture systems: (i) TCM-199 (Tissue Culture Medium-199); (ii) TCM-199+10 ng/mL FGF2; (iii) TCM-199+20 ng/mL FGF2; (iv) TCM-199+30 ng/mL FGF2; (v) TCM-199+10 ng/mL ITS; (vi) TCM-199+20 ng/mL ITS; (vii) TCM-199+30 ng/mL ITS and (viii) TCM-199+20 ng/mL ITS+20 ng/mL FGF2 in a CO 2 incubator at 38.5°C for 24 h. All the oocyte culture media were supplemented with 10% FBS, FSH (10 μg/mL) and gentamicin (50 μg/mL). The maturation rate was assessed based on the degree of expansion of cumulus cells and identifying first polar body extrusion into perivitelline space. The matured oocytes were inseminated with 1 to 2 million spermatozoa/mL in Brackett and Oliphant medium and the cleavage rate was checked after 42-48 h post insemination and further cultured for 6-7 days. Maturation and cleavage rates were significantly higher (P<0.05) in the oocytes cultured in TCM-199 +10% FBS+FSH (10 μg/mL) supplemented with both 20 ng/mL ITS and 20 ng/mL FGF2 as compared to the control. It was concluded that the supplementation of ITS and FGF2 in maturation medium was beneficial for improving maturation and cleavage rates of sheep oocytes. The addition of ITS and FGF2 in embryo culture medium did not improve the development of sheep embryos.