The effect of cadmium on the bovine in vitro oocyte maturation and early embryo development

Common pollutants such as heavy metals and cadmium is among those with high environmental concerns. In vivo studies had shown that cadmium (Cd) causes oocyte degeneration and embryo mortality, and lowers pregnancy rates in mammals. However, there is limited information available about direct effects of Cd on oocyte maturation and/or embryo development. This study was aimed to investigate if Cd has any effect on the oocyte maturation and/or embryo development in vitro. Bovine COCs were collected from the slaughter house and cultured for 24 h in serum-free media only (Controls) or supplemented with 0.2, 2.0 and 20.0 μM CdCl2. At 24 h cumulus cell expansion was assessed in all COCs. COCs were either denuded and stained for determination of nuclear maturation or fertilized for assessment of subsequent embryo development. Cd at the lowest concentration (0.2 μM) did not affect any of the parameters studied. However, at higher concentrations (2.0 and 20.0 μM) it significantly (P