Title: Effects of Time of Deoxyribonucleic Acid Microinjection on Gene Detection and In Vitro Development of Bovine Embryos
Abstract: In vivo fertilized embryos were surgically collected from superovulated dairy cows to evaluate microinjection on embryo development and utilized the polymerase chain reaction technique for selection of transgenic embryos.Seventy-two percent of the embryos with visible pronuclei or nuclei were microinjected with DNA, and the remaining 28% served as uninjected controls.All embryos were cocultured with bovine oviductal epithelial cells.Mean final development scores of embryos within the same initial cell stage at collection were unaffected by microinjection.After 144 h of culture, 45% of the microinjected embryos developed to the morula or blastocyst stage.The transgene was detected in 50, 10, and 9% of demimorulae from embryos microinjected at the 1-, 2-, and 4-ceJI stages.Frequency of transgene detection was higher in morulae from I-cell embryos than in morulae from 2-and 4-cell embryos.Use of in vitro coculture, embryo bisection, and polymerase chain reaction technique facilitated selection of bovine embryos that carried the transgene.