The microenvironment of the ovarian follicle in the postpartum dairy cow: effects on reagent transfer from cumulus cells to oocytes in vitro.

PMID 24958635


This study's hypothesis was that the nutrient composition in follicular fluid (FF) of ovarian follicles in early lactating postpartum cows may influence reagent transfer from cumulus cells (CC) to the oocyte. To test this, concentrations of amino acids (AA), cholesterol, glucose, and nonesterified fatty acids were measured in FF from the largest antral follicles at Days 21 and 46 postpartum during which time, most animals were expected to have resumed ovulatory activity. From the range of concentrations measured, two media compositions (Lac and Half-Lac) were prepared to compare with medium 199 (M199). The AA and cholesterol concentrations in FF were on average, approximately 35% and greater than 1000% higher than in M199, respectively. The nonesterified fatty acids, but not glucose, concentrations also exceeded those in M199. The transfer of fluorescent dye from CC to oocytes in bovine cumulus-oocyte complexes incubated with and without phosphodiesterase inhibitors (dipyridamole and milrinone) and/or forskolin was assessed. Maximum dye accumulation in oocytes incubated in M199 occurred after 4 hours and was further increased (Pxa0