Effects of epidermal growth factor and progesterone on oocyte meiotic resumption and the expression of maturation-related transcripts during prematuration of oocytes from small and medium-sized bovine antral follicles.

This study evaluated the effects of epidermal growth factor (EGF) and progesterone (P4) on growth, the resumption of meiosis and expression of eukaryotic translation initiation factor 4E(eIF4E), poly(A)-specific ribonuclease (PARN), oocyte-specific histoneH1 (H1FOO), oocytematuration factor Mos (cMOS), growth differentiation factor-9 (GDF9) and cyclin B1 (CCNB1) mRNA in oocytes from small and medium-sized antral follicles after prematuration and maturation in vitro. Oocytes from small (,2.0mm) and medium (3.0-6.0mm) antral follicles were cultured in medium containing EGF (10 ng mL(-1)), P4 (100 mu M) or both. After culture, growth rate, resumption of meiosis and eIF4E, PARN, H1FOO, cMOS, GDF9 and CCNB1mRNAlevels were evaluated. P4 increased cMOS, H1FOO and CCNB1mRNAlevels after the culture of oocytes from small antral follicles, and EGF increased CCNB1 mRNA levels in these oocytes. In the medium-sized antral follicles, P4 alone or in combination with EGF increased oocyte diameter after prematuration in vitro. In these oocytes, the presence of eitherEGFor P4 in the culturemediumincreasedcMOSmRNAlevels. In conclusion, P4 increasescMOS, H1FOO and CCNB1 mRNA levels after the culture of oocytes from small antral follicles. P4 and the combination of EGF and P4 promote the growth of oocytes from medium-sized antral follicles, and both EGF and P4 increase cMOS mRNA levels.