In vitro deveropment of porcine oocytes fertilized in vitro with spermatozoa preincubated in two different media

This study was conducted to clarify the effects of sperm concentration and media during preincubation on fertilization and development of porcine oocytes fertilized in vitro (IVF). The effect of porcine oviduct epithelial cell aggregates (POECA) on in vitro development of IVF embryos was also examined. Oocytes matured in vitro for 48 to 50 h were inseminated with epididymal spermatozoa preincubated at 2 sperm concentrations (1 - 2 x 10(8)/ ml vs 4 - 5 x 10(8)/ ml) for 3 h in either Dulbecco's phosphate buffered saline (PBS) or Brackett and Oliphant medium (BO). For capacitation, spermatozoa were treated with heparin (100microg / ml) for 15 min at 38.5 degrees C under 5% CO(2) in air. Cleavage and development to the blastocyst stage were evaluated on Day 3 and Day 8 after culture with or without POECA. The effect of sperm concentration on preincubation did not affect the fertilization rate, but preincubation in PBS medium did result in a higher fertilization rate (P < 0.05) than did the BO medium. The proportion of embryos undergoing cleavage and development to the blastocyst stage was significantly higher (P < 0.05) in the POECA co-culture group than in the group without POECA co-culture. The present results indicate that PBS medium can be utilized as a simple preincubation medium for porcine spermatozoa and that the presence of POECA during in vitro culture improved the development of IVF oocytes to the blastocyst stage.