Abstract
PURPOSE: Improvement of in vitro oocyte growth by addition of granulosa cells derived from differential developmental stages of follicles. METHODS: Granulosa cells (GCs) collected from either early antral follicles (EAFs) or antral follicles (AFs) were added to oocyte-granulosa cell complexes (OGCs) derived from EAFs, and the in vitro growth of the oocytes was evaluated. RESULTS: Granulosa cells were incorporated into OGCs to form new OGCs within 2 days of culture. After 14 days of culture, the number of GCs surrounding oocytes was similar among the three OGCs conditions (unmanipulated "natural OGCs," "EAF-GCs add OGCs," and "AF-GCs add OGCs"), whereas the survival rate of the GCs and diameter of oocytes grown in vitro were the greatest for "AF-GCs added OGCs." After parthenogenetic activation, developmental rate till the blastocyst stage tended to be higher for "AF-GCs add OGCs" compared with other groups. Addition of AF-GCs significantly increased a hypoxic marker (pimonidazole staining) and increased the lipid content in oocytes grown in vitro compared with unmanipulated OGCs. CONCLUSION: Addition of GCs derived from more advanced stages of follicles to the OGCs changes the metabolism of oocytes and is beneficial for in vitro growth of oocytes derived from EAFs.