Effect of short periods of sperm–oocyte coincubation during in vitro fertilization on embryo development in pigs

• Published in: Theriogenology 2004-08, Vol.62 (3-4), p.544-552
• Main Authors: Gil, Maria A, Ruiz, Maria, Vazquez, Juan M, Roca, Jordi, Day, Billy N, Martinez, Emilio A
• Format: Article
• Language: English
• Subjects: Animals; Coincubation time; cryopreservation; Cryopreservation - veterinary; embryogenesis; Embryonic and Fetal Development; Female; Fertilization in Vitro - veterinary; In vitro fertilization; Male; Oocyte; oocytes; polyspermy; Porcine; Semen Preservation - veterinary; Sperm Count; Sperm-Ovum Interactions; swine; Swine - embryology; Time Factors
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/j.theriogenology.2003.11.001

The present study was conducted to determine if the efficiency of in vitro pig embryo production could be improved by a reduction in the period of time that oocytes are exposed to sperm during in vitro fertilization. A total of 1596 immature cumulus–oocyte complexes from five replicates were matured in vitro and inseminated with frozen–thawed spermatozoa (2000 spermatozoa/oocyte) for 10, 30, 60min or 6h (control group). The oocytes from short coincubation times were washed three times in fertilization medium to remove spermatozoa not bound to the zona and transferred to another droplet of the same medium (containing no sperm) for 6h. After 6h, the oocytes from each group were cultured in embryo culture medium for another 6h to assess fertilization parameters and for 7 days to assess embryo development. After each period of coincubation, some oocytes were stained with Hoechst-33342 to count zona-bound sperm. Although the number of zona-bound sperm increased with the coincubation time (34.1±1.7, 46.8±2.8, 62.8±3.8, and 139.5±6.1 for 10, 30, 60min and 6h, respectively, P