Effects of Timing on Cell Biopsy From Pre-Compacted Morula Stage Bovine Embryos on Subsequent Embryonic Development

Introduction: embryo biopsy has potential applications in molecular researchprocesses in domestic animals, besides its application in sex determination in embryotransfer programs. the objective of the present study was to assess the in vitrodevelopment of bovine embryos biopsied on different days of precompacted morulastage.materials and methods: slaughterhouse-derived oocytes were matured in vitro,fertilized (day-0) by frozen-thawed, percol-separated spermatozoa and cultured onoviductal cell monolayer. the embryos were subjected to cell biopsy on days 2, 3, and4 postinsemination at 4-16-cell stages. the data were analyzed using anova andchi-squared tests (sigmastat, version 2). a p-value < 0.05 was considered significant.results: biopsies carried out at 16-cell stage (day-4) resulted in 94% of embryosdeveloping to the blastocyst stage, which was significantly higher (p < 0.05) than theones biopsied at 8-cell stage on day-4 (64%), and those undergoing the procedure onday-3 (49% and 46% at 4-cell and 8-cell stages, respectively) and day-2 (39% and33% at 4-cell and 8-cell stages, respectively). no significant differences wereobserved between biopsied and non-biopsied embryos on a given day. the total cellnumber in biopsy-derived blastocysts ranged between 103 and 135. the difference inthe number of total cells, dead cells and cell allocation to trophectoderm and inner cellmass between non-biopsied and biopsy-derived blastocysts was insignificant.conclusion: biopsy of bovine embryos at 4-16-cell stages had no adverse effects onin vitro developmental potentials and the 16-cell stage embryos, biopsied on day-4was the best stage for blastomere removal.