INFLUENCE OF COOLING ON THE INCIDENCE OF ANEUPLOIDY OF IN VITRO MATURED BOVINE OOCYTES

Abstract

The objective of the study was to verify the incidence of bovine aneuploid oocytes when cooled. Bovine cumulus-oocyte complexes were recovered from ovaries at a slaughterhouse and then divided into five groups: control group (uncooled oocytes), 0/4 h group (composed of oocytes cooled before the onset of maturation at 4ºC), 0/29 (composed of oocytes cooled before the onset of maturation at 29 ºC ), 12/4 (cooled 12 h after the onset of maturation at 4ºC), and 12/29 h group (cooled 12 h after the onset of maturation at 29 ºC). The oocytes remained cooled for 45 min. In all groups, the oocytes completed 24 h of maturation. Subsequently, the cumulus cells were removed, and the denuded oocytes fixed on slides and stained with aceto-orcein. No differences (P > 0.05) in the incidence of aneuploid metaphase II oocytes were observed between the control group (0/21; 0%) and oocytes cooled at 4ºC and 29 ºC before (3.8% and 6.8%) and after 12 h the onset of maturation (12.5% and 10%). It is concluded that the cooling at 4 and 29 °C before the maturity or 12 after not affect the rate of aneuploidy of bovine oocytes, after completing 24 hours of in vitro maturation.