Influence of Follicular Fluid on <i>in Vitro</i> Maturation and Fertilization of Bovine Oocytes

Abstract

The aim of this study was to investigate the effect of time on in vitro maturation of bovine oocytes and of the addition of follicular fluid on meiotic progression. The cumulus-oocyte complexes (COCs) collected from 3 to 6 mm follicles were obtained from ovaries of slaughtered female animals. The medium of maturation was supplemented or not with 20 μL follicular fluid (FF); 661 oocytes were matured in vitro (extrusion of the first polar corpuscle) for 22 hours with added follicular fluid (AFF) (72.01%) or without follicular fluid (WFF) (67.53%) and 679 oocytes were matured in vitro for 26 hours (extrusion of the first polar corpuscle) with AFF (92.1%) and WFF (77.15%). The results of extrusion of the second polar corpuscle as an event related to the fertilization percentages showed that the increase in the fertilization rate is maintained at 26 hours with AFF (79.45%), but the percentage decreases WFF (65.08%). After 22 hours, the fertilization rate was 62.38% AFF and 53.40% WFF. The developmental competence of bovine oocytes is affected by the duration of maturation in vitro and the inclusion in the FF culture medium. The use of follicular fluid in the in vitro maturation medium may be a biological strategy to increase the cumulus expansion, the nuclear maturation and the in vitro fertilization.