Influence of Follicular Wall on Meiotic Resumption of Bovine Oocytes When Cultured Inside or Outside Hemi-Sections.

Abstract

We evaluated the importance of the attachment of the oocyte to the granulosa layer, using co-culture of follicular hemi-sections with groups of 10 COCs (cumulus-oocyte complexes) or 10 DOs (denuded oocytes) and oocytes cultured within their own half-follicle. Various prod-ucts acting on protein phosphorylation (IBMX, PMA, H-7) and cellular differentiation (estrous serum, FSH, LH or estradiol) involved in follicular and nuclear maturation were also used to evaluate their effect on the capacity of the follicular wall to inhibit meiosis resumption. When oocyte were cultured within their own half-follicles, none of the treatments used in this study could significantly reverse the inhibitory action of the follicular wall on the meiotic resumption. When the contact between the oocyte and the hemi-section was ruptured (co-culture of COCs and DOs), oocytes responded differently according to whether they were surrounded or not with their cumulus cells, and inhibition of meiosis was lowered particularly with LH and PMA with COCs. These results show that the communication junctions between the oocyte and the follicle are important for the inhibitory action of the follicle and this contact between both overcome the effect of any treatment applied.