ICR female mice aged 3 to 4 weeks, were stimulated with 7.5IU PMS injection. At 48-52h post-PMS injection, ovaries were dissected out and oocytes-cumulus complexes (OCCs) were divided into three groups, cumulus-free oocytes (O), cumulus-free
cocultured
with cumulus cell (O+C) and OCC. The oocyte were cultured in TCM199 containing various protein sources, FCS, BSA or PVP with gonadotropins (Gns) for 24h. Spermatozoa were collected from cauda epididymis and capacitated in T6+BSA for 2h. After
oocyte
maturation in vitro (IVM) in different experimental groups, matured oocytes were inseminated with the capacitated spermatozoa in T6+BSA for 6h. In the groups of IVM in TCM+BSA or PVP, fertilization (IVF) did not occur efficiently. However,
increased
fertilization was found in TCM+FCS group. The oocytes groups, with cumulus cells showed decreased polyspermy in FCS group (O; 31.8%, O+C; 12.2%, OCC; 16%), the addition of Gns did not prevent polyspermy in al three groups. The rates of
fertilization
increased in zona-free oocytes in PVP group. This results showed that culture system for IVM and IVF could be improved. Furthermore, PVP can be used for the substitution of protein source during maturation, and its low rate of fertilization has
been
found due to zona hardening which occurred in FCS-free medium.
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