Ovine follicular fluid inhibits aromatase activity.

"Within follicle" regulations may be important for the fine tuning of gonadotrophin action in ovarian follicles. While numerous growth factors, steroids or proteins which are present in follicular fluid have been shown to have the ability of positively or negatively affecting follicle function, the net effect of follicular fluid of the dominant follicle on its function is unclear.A bioassay measuring aromatase activity of follicular walls was used (1) to check whether follicular fluid from dominant follicles can alter aromatase activity (2), to check how follicle size, atresia and specific gonadotrophins alter the effects of follicular fluid (3), to identify the nature (steroid or protein) of the active compound(s), and (4) to check whether the inhibition is specific of aromatase.

Presence of an aromatase inhibitor, possibly heat shock protein 90, in dominant follicles of cattle.

In cattle, it has been suggested that follicular fluid has direct modulatory effects on follicular growth and maturation. In the first part of this study, an in vitro test using aromatase activity of follicular wall fragments as an end point was validated for cattle follicles and was used to test whether follicular fluid (from dominant or non-dominant follicles) modulates aromatase activity. Fluid from dominant follicles at a concentration of 24 or 12% (obtained during the luteal and follicular phases, respectively) significantly inhibited aromatase activity.

Aromatase activity of human granulosa cells in vitro: effects of gonadotrophins and follicular fluid.

The aim of this study was to assess whether human dominant follicular fluid has the ability to modulate aromatase activity and/or granulosa cell proliferation. Dominant follicular fluid was obtained by laparoscopy before the luteinizing hormone surge in naturally cycling women while granulosa cells used in the tests were obtained from in-vitro fertilization patients. Aromatase was measured by the tritiated water release assay, following a 48 h incubation with follicular fluid and serum, and expressed for 5x10(4) granulosa cells.