Is follicular fluid steroid content representative of follicular steroid secretion?

Nine oestrogen-active (E-A) and seven oestrogen-inactive (E-I) bovine follicles were superfused for 10 h. Levels of oestradiol (E2), testosterone (T) and progesterone (P4) were measured in superfusate and follicular fluid. No correlation between intrafollicular steroid concentrations of E2, T and P4 and the amount of these steroids detected in the superfusate was found in oestrogen-active follicles, i.e. follicular fluid E2, T or P4 levels did not allow for any prediction of superfusate E2, T and P4 concentrations and vice versa. In contrast, E-I follicles showed a close correlation between intrafollicular and superfusate T and P, but not E2 levels. It is speculated that an alteration in intrafollicular regulatory mechanisms might explain the different findings for these two classes of follicles.