Abstract
Chromosomal analysis was accomplished in bovine embryos derived from in vitro fertilization (IVF) after insufficient in vitro maturation of oocytes. Bovine oocytes collected from different donors were pooled into two groups; oocytes matured in vitro for 12 hrs were classified as the 12-hr group (insufficient maturation group), and other oocytes matured in vitro for 26 hrs were classified as the 26-hr group. At forty-eight hrs after IVF, most of the embryos (185/223, 83%) in the 26-hr group developed into the 8- or 16-cell stages, while many embryos (125/165, 75.8%) in the 12-hr group were at the 2- or 4-cell stage. The incidence of chromosomally abnormal embryos in the 12-hr group, 66.7% (54/81), was significantly higher than that in the 26-hr group, 27.8% (20/72). These chromosomal anomalies were haploids, polyploids and mixoploids. It was presumed that the increase in these anomalies was caused by sperm penetration with dysfunction of zonae pellucida and/or membrane of the ooplasm of immature oocytes.
