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PurposeImprovement of in vitro oocyte growth by addition of granulosa cells derived from differential developmental stages of follicles.MethodsGranulosa 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.ResultsGranulosa 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.ConclusionAddition 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.

Purpose This study aimed to examine the relationship between granulosa cells (GCs), number of follicles, and the ability of follicular fluid to support in vitro growth of oocytes. Methods The culture medium was supplemented with follicular fluid (FF) collected from GC‐rich ovaries and GC‐poor ovaries, and its effect on in vitro growth and quality of oocytes derived from early antral follicles (EAFs) was assessed. Results GC‐rich FF treatment enhanced oocyte growth and augmented changes in the chromatin configuration and lipid content of oocytes when compared to oocytes treated with GC‐poor FF. Moreover, oocytes treated with GC‐rich FF had a higher ability to progress to the blastocyst stage, than oocytes derived from large antral follicles (3‐5 mm in diameter). In addition, supplementation of the culture medium with either GC‐rich or GC‐poor FF enhanced histone acetylation in oocytes grown in vitro. Conclusion GC‐rich FF contains key factors that support in vitro oocyte growth; hence, oocytes grown in GC‐rich FF medium had high developmental competence, which was comparative to the oocytes grown in vivo.

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This study compared the effects of different volumes of culture medium for the in vitro growth of oocytes derived from porcine early antral follicles (EAFs). Oocyte granulosa cell complexes (OGCs) were collected from EAFs (0.5–0.7 mm in diameter) and individually cultured for 14 days. When OGCs were cultured in 1 ml of medium with or without polyacrylamide gel (PAG), the presence of PAG supported granulosa cell (GC) proliferation and oocyte growth. When OGCs were cultured in 0.2 or 1 ml of medium on PAG, the number of GC in the OGC culture and the developmental ability of the oocytes cultured in vitro were significantly higher for the 1 ml of culture medium group than for the 0.2 ml group. In conclusion, a combination of a large volume of culture medium with PAG improved the growth and developmental ability of the oocytes cultured in vitro , which were comparable to the oocytes collected from large antral follicles.