Abstract: BACKGROUND AND AIM: To explore the effects of folic acid (FA) on in vitro maturation of mouse oocytes. MATERIALS AND METHODS: Naked mouse oocytes were matured in vitro either spontaneously(M16) or in the presence of hypoxanthine (Hx) or Hx plus FA for 24 h. At the end of the culture period, the nuclear status of mouse oocytes was assessed under inverted microscope. Immunoflurescence staining was used to evaluate the chromosome and spindle configuration of oocytes. RESULTS: The rates of germinal vesicle breakdown (GVBD) were 98％,22.2％,40.1％and the rates of the first polar body (PB1) extrusion were 77.7％,15.5％,27.6％ for M16,Hx and FA groups,respectively. The rates of GVBD and PB1 were all increased with the addition of FA compared with the Hx groups and comparison was significant (P<0.05). Hx and FA did not influence chromosome, but FA reversed the size of metaphase spindle elongated by Hx. CONCLUSION: FA appeared to promote the resumption of meiosis and subsequent maturation of mouse oocytes in vitro.

Key words: folic acid, oocyte, mouse