In vitro culture of isolated preantral and antral follicles of goats using human recombinant FSH: Concentration-dependent and stage-specific effect

The present study aimed to investigate a concentration-response curve of human recombinant FSH (hrFSH) for in vitro culture of isolated preantral and early antral follicles of goats. Isolated follicles were cultured for 18 days using the following treatments: basic culture medium (control); or control medium supplemented with 10, 50, and 100 mIU/mL of hrFSH. At the end of the culture, cumulus-oocyte complexes were recovered and subjected to in vitro maturation. The following endpoints were evaluated: follicle morphology, growth rate and antrum formation, oocyte viability and meiotic stage, and estradiol production, as well as relative expression of FSH receptor (FSHR), and steroidogenic enzyme (3β-HSD, CYP17, and CYP19A1) genes. In antral follicles, the FSH addition at 50 mIU/mL increased follicular diameter and growth rate, percentage of fully developed oocytes, and oocyte diameter (P <  0.05), and tended to increase the percentage of MII oocytes when compared to the control (P =  0.07). With preantral follicles, FSH addition at 100 mIU/mL increased relative abundance of mRNA for CYP19A1 when compared to the control (P <  0.05). At the same FSH concentrations of 100 and 50 mIU/mL, there was a greater relatively abundance of mRNA for 3β-HSD and CYP17 in preantral than in antral follicles (P <  0.05). For preantral and antral follicle comparisons when the same treatments were imposed, there were greater concentrations of estradiol for antral follicles (P <  0.05). In conclusion, hrFSH enhanced in a concentration-dependent manner the in vitro development of caprine antral follicles; however, there was no positive effect in the culture of preantral follicles.