These results also suggest that the presence of binucleate cells observed in the present study is due to abnormal polymerization of actin filaments, which results in nuclear division without cytoplasmic division. In addition, asynchronized nuclear and cytoplasmic division (as shown in Figs. 4 and 5) indicates that culture conditions may delay the progression of polymerization and depolymerization of microfilaments. Most cells keep a large pool of G-actin (nonfilamentous actin) to maintain the ability to quickly reorganize the F-actin (filamentous actin) when subjected to environmental changes. It is not clear whether pig oocytes or embryos synthesize sufficient actin protein during oocyte maturation and early development. The examination of G-actin synthesis in pig oocytes and embryos may be helpful to determine why in vitro-produced embryos have less filamentous actin. Cheap Diskus Advair
In summary, the present study indicates that poor developmental ability and decreased number of cells in pig embryos produced in vitro are due to abnormal cleavage during development. Abnormal cleavage starts at the first cell division. One of the most typical abnormal morphologies is embryo fragmentation. No fragmentation was observed in in vivo-derived embryos. The differences in microfilament distribution observed in this study between in vivo and in vitro embryos suggest that conditions for oocyte maturation and activation, and especially for embryo culture, which mediate more normal actin microfilament distribution may reduce embryo fragmentation and result in an improvement in quality of in vitro embryos.