Follicular factors determining the developmental competence of porcine oocyte

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.