Development of bovine embryos on Vero/BRL cell monolayers (mixed co-culture)

The objective of this study was to test a new co-culture system of bovine e mbryos, which we call "mixed co-culture." This system consists of culturing embryos on cell monolayers composed of both Vero and BRL cells (Vero/BRL). Cumulus-oocyte complexes from ovaries of slaughtered cows were matured and fertilized in vitro. The presumptive zygotes were cultured with Vero/BRT, (Group 1), BRL (Group 2) or Vero (Group 3) cell monolayers, in 40 muL drops of Menezo B2 medium supplemented with 10% FBS and antibiotics. The develop ment of the presumptive zygotes was compared on Day 2 [48 h post inseminati on (pi)] and Day 7 (168 h pi). On Day 2, there was no difference between th e groups. On Day 7, the highest percentage of compacted morulae/blastocysts was observed in mixed co-culture of Vero/BRL cells: 40% versus 36% on BRL versus 27% on Vero cell monolayers. The differences were statistically sign ificant (P less than or equal to0.05). Among compacted morulae/blastocysts, blastocysts prevailed in mixed co-culture: 67% on Vero/BRL as compared wit h 55% on BRL and 27% on Vero cell monolayers. The differences were highly s tatistically significant (P less than or equal to0.01). The results suggest that Vero/BRL cells improve the development of bovine embryos. (C) 2000 by Elsevier Science Inc.