239 CANINE OOCYTES CAN BE SPONTANEOUSLY PARTHENOGENERATED AND DEVELOPED TO 2-CELL TO 8-CELL STAGE PARTHENOGENERATED EMBRYOS IN COCULTURE SYSTEM WHICH THEY WERE COCULTURED WITH OVIDUCT CELLS OR OVIDUCT EXTRACTS

Abstract

The objective of this study was to coculture canine oocytes with oviduct cells or oviduct extracts in modified M199 culture medium to improve the MII rate. The canine oocytes were collected from the local slaughterhouse and were cultured in three culture systems while in the same culture medium. In culture system A, canine oocytes were cocultured with ‘small-round’ oviduct cells and ‘big-round’ oviductal cells which based on cell volume and morphology for 96 h. In culture system B, canine oocytes were cultured with in the modified M199 medium with 10% canine follicle fluid (in the CEF group) or without canine follicle fluid (in the compared group) for the first 6 h; following this, they were cocultured with ‘small-round’ oviductal cells for another 90 h, which were preblanced at least 2 h. In the culture system C, the canine oocytes were cocultured with canine estrous oviduct extracts for 96 h (in the compared group) or were cocultured with granulosa cells together with canine estrous oviduct extracts (in the G + CEOE group) for 96 h. These results demonstrated that, in culture system A, one 2-cell and one 8-cell stage parthenogenerated embryo in the small-round group and one 2-cell stage parthenogenerated embryo in the compared group were achieved after in vitro culture for 96 h. Meanwhile, the MII rates were greater in small-round group (47.1%) than that in big-round group (36.1%) and the compared group (32.4%). In the culture system B, one 3-cell stage parthenogenerated embryo was detected in CEF group. The MII rates were almost equal in CEF group (28.0%) and in the compared group (26.1%). In culture system C, one 2-cell stage parthenogenerated embryo was found in the compared group. The MII rate were almost equal in CEOE group (25.8%) and in the G + CEOE group (23.5%). It is concluded that some unidentified factors secreted by the oviductal cells or oviduct extracts may promote the development of canine oocytes in vitro and parthenogenerate the canine oocytes beyond 2-cell stage parthenogenerated embryos. The culture system in which the canine oocytes were cocultured with oviducts or oviductal cells has been improved to date.