STIMULATION OF DEVELOPMENT OF IN-VITRO-MATURED AND IN-VITRO-FERTILIZED BOVINE EMBRYOS BY PLATELETS

In vitro-fertilized bovine embryos were incubated in Menezo's B2 mediu m (MB2) supplemented with 2 mg/mL of BSA. In Exp. 1, eight-cell stage embryos were allotted to one of the following groups: control medium ( MB2), MB2 with 20 ng/mL of platelet-activating factor (PAF), 1 X 10(7) bovine blood platelets (Platelets), oviductal cells (BOEC), BOEC and 20 ng/mL of PAF (BOEC + PAF), or BOEC and 1 X 10(7) platelets (BOEC Platelets). In Exp. 2, eight-cell embryos were allotted to one of the following groups: control medium (MB2), MB2 with 1 X 10(7) platelets ( Platelets), 1 X 10(7) platelets and 10 mug/mL of platelet-derived grow th factor antibody (Platelets + anti-PDGF), 1 X 10(7) platelets and 1 mug/mL of indomethacin (Platelets + Indomethacin), or 1 X 10(7) platel ets and 3 mug/mL of mianserin (Platelets + Mianserin). Embryos were in cubated at 39-degrees-C in 5% CO2 in groups of five until 8 d after in vitro fertilization (IVF). In Exp. 1, Platelets stimulated embryo dev elopment to the morula, blastocyst, and expanded blastocyst stages. Em bryo development was greatest in the BOEC + Platelets group on d 7 and 8 after IVF. Only embryos incubated in the BOEC + Platelets treatment group reached the hatched blastocyst stage on d 8. In Exp. 2, embryos incubated in the Platelets treatment group had the greatest (P < .05) proportion develop beyond the eight-cell stage. Embryos incubated in the Platelets + anti-PDGF group had less (P < .05) development beyond the eight-cell stage and to the morula stage. These results indicate t hat the stimulatory effects of PDGF on bovine embryo development may b e derived from both the oviductal epithelium and platelets.