Exogeneous substances affecting development of in vitro-derived bovine embryos before and after embryonic genome activation

Three experiments were conducted to evaluate how exogenous substances [feta l bovine serum (FBS), arachidonic acid (AA), glutathione (GSH), platelet-de rived growth factor (PDGF), transforming growth factor-beta (TGF), fibrobla st growth factor (FGF), insulin, transferrin and selenium (ITS)] affect pre implantation bovine embryo development. Cumulus-oocyte complexes (COC) were matured and fertilized in vitro, and their development was monitored up to 192 h post insemination in a two-step culture system. In Experiment 1, ins eminated oocytes were cultured in modified bovine embryo culture medium (mB ECM) supplemented with FBS or BSA for up to 60 h post insemination, and the resultant 8-cell embryos were then cultured singly in mBECM supplemented w ith AA+GSH+PDGF+TGF. More (P<0.005) blastocysts were derived from 8-cell em bryos produced in media containing FBS than BSA. In Experiment 2, the 8-cel l embryos produced in mBECM supplemented with FBS were cultured singly in m BECM as follows: If no supplementation; 2) AA and GSH or 3) AA, GSH, PDGF a nd TGF. Compared with no supplementation, a significant (P<0.05) increase i n the proportion of 16-cell embryos and morulae was obtained after the addi tion of either AA+GSH or AA+GSH+PDGF+TGF. In Experiment 3, oocytes were cul tured singly in mBECM as follows: 1) no supplementation; 2) AA+GSH+PDGF+TGF ; 3) AA+GSH+PDGF+TGF and FGF; 4) AA+GSH+PDGF+TGF and ITS; 5) AA+GSH+PDGF+TG F, FGF and ITS or 6) FBS. Eight-cell embryos grown in each system were subs equently cultured singly in mBECM with AA+GSH+PDGF+TGF. More (P<0.05) 16-ce ll embryos were obtained in medium supplemented with either AA+GSH+PDGF+TGF and ITS or FBS than in unsupplemented medium. Fewer (P<0.05) oocytes devel oped to the 8-cell stage with the addition of AA+GSH+PDGF+TGF and FGF than without. In conclusion, embryo development to the blastocyst stage is regul ated by exogenous AA, GSH, PDGF, FGF and ITS in a stage-specific manner. (C ) 2000 by Elsevier Science Inc.