| dc.description.abstract | Many researches have been performed to culture oocytes from follicles of 2-6mm for in vitro maturation. However, it has been reported that the ability of growing oocytes from preantral follicles (2-3mm) to acquire full meiotic competence after in vitro maturation is at relatively low rates compared to fully-grown oocytes from antral follicles (4-6mm). It is a challenge to scientists to find out a suitable culture conditions to increase the rate of growing oocytes becoming matured. The aim of this research is to preculture porcine oocytes from preantral follicles (2-3 mm) for in vitro growth (IVG) before in vitro maturation (IVM). In the research, the meiotic competence of growing oocytes from preantral follicles (2-3 mm in diameter) was investigated by IVG for 24 hours and subsequently IVM for 42 hours. Oocytes were collected by dissection and cultured in medium supplied with 0.01IU/ml follicle stimulating hormone (FSH), 1mM dibutyl cyclic AMP (dbcAMP), 0.001mg/ml 17β estradiol and 5% follicular fluid. The results showed that growing oocytes were able to reach to fully grown (GVI) stage after IVG with high percentage (73.1%), whereas oocytes before IVG obtained low percentage of GVI (4.5%). There was a significant difference between cumulus cell expansion in the group of oocytes undergoing IVG and IVM and the group cultured for only IVM (83.6% and 53.4%, respectively). Especially, we obtained full meiotic competence of grown oocytes after IVG and IVM which was similar to fully grown oocytes after IVM (35.2% and 40.6%, respectively). Therefore, it is suggested that oocytes from follicles of 2-3mm in diameter are required to be cultured for 24 hours of in vitro growth before in vitro maturation to obtain high rate of oocytes progress to mature (MII) and extrude first polar body.
Key words: preantral follicles, porcine growing oocytes, in vitro growth, in vitro maturation | en_US |
