Developmental competence of bovine IVM/IVF oocytes under different co-culture conditions

Abstract

The experiment was carried out to compare the influence of different culture systems on the developmental potential of bovine embryos derived from IVM/IVF oocytes. The investigations included comparison of the developmental competence of IVM/IVF zygotes derived from oocytes cultured in large (>30 oocytes/well) and small (1-5 oocytes/drop of medium) groups and co-cultured with: Buffalo rat liver cells (BRL), African Green monkey kidney (VERO) and bovine oviduct epithelial cells (BOEC). The highest number of embryos derived from IVM/IVF oocytes maturing in large groups developed to blastocysts in co-culture with VERO (45.9%), followed by BRL (30.9%) and BOE (36.1%) cells. The hatching ability of these blastocysts did not differ significantly for BRL and VERO co-cultures (respectively 74.5 and 58.0%) and was significantly lower for those co-cultured with BOEC (34.7%). In contrast to the oocytes maturing in large groups, the developmental competence of oocytes of the small group cultures was independent of the feeder layer used for co-culture and 19.4 to 27.1% of these oocytes reached the blastocyst stage. No significant differences were noticed in either the blastocyst rates or in the hatching ability of these blastocysts developing in co-culture with BRL, VERO and BOE cells. The mean number of cells in the blastocyst of the large group culture developing in co-culture with BRL cells on day 8 was 112.0±27.7 while the blastocysts developing in co-cultures with VERO and BOE cells contained 76.8±20.0 and 94.0±23.6 cells, respectively.