In vitro fertilization of bovine oocytes matured in vivo and collected at laparoscopy

Abstract

Laparoscopy was used to collect 1618 in vivo-matured bovine follicular oocytes. Inexperienced laparoscopists encountered difficulties such as intestine perforation or failure to enter the peritoneal cavity. The recovery rate of oocytes was lower for beginners (53–59%) than for experienced laparoscopists (72–79%). 975 follicular oocytes were inseminated in vitro using spermatozoa exposed to a high ionic strength medium. Oocytes surrounded by expanded cumuli were fertilized and cleaved more frequently (P<0.001) than oocytes without cumulus or corona cells and oocytes surrounded with compact cumuli or corona cells. Only 4.5% of in vitro-fertilized oocytes that cleaved progressed to the 16-cell stage in vitro. None of these resulted in pregnancy after transfer to the oviducts of recipient cows. By contrast, up to 37% of in vitro-fertilized eggs were at the 16-cell stage after incubation in rabbit oviducts. Surgical or non-surgical transfer of these embryos to the uterine lumen resulted in 6 calves born out of 13 transfers. Pregnancies were obtained after transfer of 16-cell and morula stage embryos. There was considerable inter-experiment variation caused by variable oocyte quality from one oocyte donor to another. It should be possible in the near future to overcome those difficulties and apply this methodology in veterinary medicine.