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.