engleski

IN VITRO DEVELOPMENTAL COMPETENCE OF EMBRYOS DERIVED FROM TRANSVAGINAL ULTRASOUND OOCYTE ASPIRATION IN CYCLING COWS AND FROM SLAUGHTERHOUSE OVARIES

The present study was conducted to assess the embryo developmental competence of oocytes recovered from slaugtherhouse ovaries (SO) and those aspirated from cycling cows using transvaginal ultrasound ovum pick-up technique (OPU). The study was conducted during September 2000 year. Cumulus oocyte complexes (COCs) were collected from ovaries of slaughtered Simmental cows. Aspiration of antral follicles was performed within 2 to 4 hours after slaughter. The transvaginal ultrasound-guided (Pie Medical, the Netherlands) oocyte collection was performed in four cycling Simental donor cows, twice a week for four consecutive weeks (8 OPU sessions per cow). Oocytes were matured in vitro in TCM 199 bicarbonate medium supplemented with 10% FSC, FSH/LH (PergonalŇ 75/75 I.U., Serono), 1 mg/ml estradiol-17b and 100 mM cisteamine. After 24 hours of incubation at 39oC and with 5% CO2 in air, matured oocytes were fertilized in vitro with frozen/thawed bull semen prepared on discontinous Percoll gradient. Cleaved embryos were cultured in vitro in SOFaaBSA medium at 39oC in atmosphere of 5% CO2, 7% O2 and 88% N2 till the Day 10. The medium was changed every second day. Cultured embryos were evaluated morphologically according to IETS standards. Results are presented as mean percentage value (&plusmn ; S.E.M.) and Chi-Square Test was used to compare the developmental competence of SO and OPU-derived embryos. A total of 198 Grade 1 and 2 oocytes were selected for IVM from 30 SO ovaries. In 8 OPU sessions from four cycling donor cows a total of 89 G1 and G2 oocytes were aspirated. Fertilization rate was 79.6 &plusmn ; 6.7% for SO and 71.7 &plusmn ; 4.2% for OPU-derived oocytes. Embryos cultured in vitro from OPU-derived oocytes developed to the morula/blastocyst stage (Day 7) at significantly higher rate than SO-derived oocytes (51.0 &plusmn ; 4.3% vs 33.4 &plusmn ; 5.9%, P<0.05), and significantly higher proportion of embryos hatched on the Day 10 of culture (22.5 &plusmn ; 7.2% vs 11.8 &plusmn ; 3.5%, P<0.05). In conclusion, embryos derived from living cows seem more able to develop in vitro until hatching than embryos derived from slaugthered animals.

Cow; oocyte; in vitro fertilization; ovum pick-up

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