In Vitro Fertilization and Development of in Vitro Versus in Vivo Matured Rabbit Oocytes

Abstract

This study was carried out to evaluate the effect of adding two types of serum, bovine serum albumin (BSA) and doe rabbit serum (DRS) to maturation tissue culture medium on the in vitro maturation rate of follicular oocytes of rabbits, and to, evaluate the success rate of in vitro fertilization and development of in vivo versus in vitro mature rabbit oocytes. About 245 immature complete cumulus oocytes were recovered immediately from ovaries of sacrified rabbit does treated with PMSG (75 IU) for 48 h. Maturation medium supplemented with 10% DRS, 6% BSA or without serum (control) were used. In vitro (n= 245) and in vivo (n=264, collected from oviduct of does sacrified after 12 h of 0.02 ml GnRH injection) mature oocytes were used for in vitro fertilization and embryo development evaluation. Results revealed that TCM-199 plus DRS increased the percentage of oocytes at M I (25 vs.15%, P<0.05) and M II (55 vs. 47.5%, P>0.05) as compared to control TCM, respectively. However, TCM-199 plus BSA had more positive effect on in vitro maturation of oocyte in term of the lowest percentage of oocytes at germinal vesicles and germinal vesicles break down (0.0 and 9.4%) and the highest one (73%, P<0.05) at M II. Fertilization rate was higher (P<0.05) for in vivo than in vitro mature oocytes (86.3 vs. 62.5%). Percentage of embryos 4-cell stage decreased (18.3 vs. 34.7%, P<0.05) and at morula stage increased (30.5 vs. 16%, P<0.05) for in vivo as compared to in vitro matured oocytes. However, the percentages of embryos at 2-cell and 8~16-cell stages between in vivo and in vitro matured oocytes were not different. The current study obtained an appropriate rate of success for in vitro fertilization (62.5%) of in vitro mature rabbit oocytes with about 16% of them were developed to morula stage (transferable embryos) versus 86.3% of in vivo mature oocytes were fertilized with about 30.5% of them at morula stage. Based on the foregoing results of this study, addition of 10% of bovine serum albumin (BSA) to tissue culture medium had more beneficial effects on in vitro maturation rate of rabbit oocytes than that occurred with 10% of doe rabbit serum (DRS). In vitro maturation with 10% BSA showed success with satisfied in vitro fertilization rate and embryos at morula stage, but still to have lower developmental competence to fertilize in vitro than in vivo matured and in vitro fertilized oocytes.