Transfer of in vitro produced sheep embryos

Abstract

The objective of the present study was to transfer sheep embryos produced in vitro to recipient ewes. Ovaries were taken from slaughtered Kivircik ewes and transferred to the laboratory in phosphate buffered saline (PBS) at 30-35degreesC. The cumulus-oocyte complexes were obtained by slicing and washing 1-6 mm diameter follicles and matured for 24 h in medium 199 supplemented with sodium pyruvate, follicle stimulating hormone (FSH), luteinizing hormone (LH) and 10% fetal calf serum (FCS) at 38.5degreesC under 5% CO2 in humidified atmosphere. Fresh semen was collected from three Kivircik rams, pooled and prepared for in vitro fertilization by the percoll-gradient method. Matured oocytes were transferred into synthetic oviduct fluid (SOF) based fertilization medium supplemented with 2% sheep oestrous serum (SES) and co-incubated with semen (0.8 x 10(6) spermatozoon/ml) for 20-21 h. After fertilization, presumptive zygotes were transferred into SOF medium and incubated for 8 days under an atmosphere of 5% CO2, 5% 02 and 90% N-2 at 38.5degreesC. Glucose (1.5 mM) was added to the culture medium on day 4. In culture, embryos were checked for cleavage and embryo development on days 4 and 8, respectively.