Murine immature oocytes were cultured in vitro in Ham´s F-10, MEM, or WM solution with or without either FCS or BSA supplement. The effect on maturation and fertilization of the immature oocytes was evaluated. Also the effect of FCS on maturation of cumulus, zona pellucidae, or oocyte was evaluated.
The results obtained were as follows
1. Fewer eggs were fertilized when Ham´s F-10, MEM or WM solution without FCS or BSA supplement.
2. Addition of FCS (10％, v/v) to Ham´s F-10 or MERCI solution increased fertilization of mouse oocytes matured in vitro as well as that of ovulated oocytes (control)
3. Addition of BSA (5-20 mg/ml) to Ham´ s F-10 or MEM solution failed to increase fertilization of mouse oocytes matured in vitro.
4. Addition of FCS or BSA to WM solution failed to increase fertilization of mouse oocytes matured in vitro.
5. Addition of FCS to Ham´s F-10 solution increased fertilization of mouse oocytes matured in vitro with the increase in the concentration of FCS.
6. Addition of FCS to Ham´s F-10 medium for oocyte maturation improved cumulus expansion, incidence of sperm penetration through zona pellucidae, shortened the time of enzymatic dissolution of the zona pellucidae, formation of the male pronucleus and resumption of meiosis
These results suggest that FCS is found necessary for in vitro maturation and fertilization of mouse immature oocytes and it also improved the maturation of cumulus, zona pellucidae, oocyte´s cytoplasm and oocyte´s nucleus.
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