Objective:To investigate the in-vitro maturation time

in vitro fertilization

2 cell and 4 cell rate of the immature oocytes after the use of HCG(human chorionic gonadotropin).Methods:The germinal vesicle(GV) immature oocytes were acquired from the ovaries of the HCG(human chorionic gonadotropin)-stimulated and non-HCG-stimulated rats.Immature oocytes were cultured in culture media.Observations were made for the status of germinal vesicle break-down(GVBD) and the extrusion of the first polar body(PB1).The achieved MⅡoocytes were then inseminated in-vitro;and the pronuclei(PN) and the pre-implantation development were observed.Results:Observations showed that after being cultured via in-vitro maturation in culture media for 16 hours

the GVBD in the GV cumulus-oocyte complexes(COC) occurring in the HCG-stimulated group had better outcomes than in non-HCG-stimulated group(P<0.01).After being cultured for 20 hours the GVBD occurring in the HCG-stimulated group had better outcomes than in non-HCG-stimulated group(P<0.01).After being cultured for 24 hours

the elimination ratio of PB1 in the HCG-stimulated group was higher than that of the non-HCG-stimulated group(P<0.01).The fertilization rate of the oocytes in the HCG-stimulated group was higher than that in non-HCG-stimulated group(P<0.05).Conclusion:Stimulation with HCG can speed up the maturation of the oocytes

and enhance the fertilization rate.