Ex ovo electroporation for gene transfer into older chicken embryos.

In ovo electroporation is an excellent method to ectopically induce or inhibit gene expression in chicken embryos and to study the in vivo function of genes during embryonic development. However, the application of electroporation in ovo to date is limited to an early stage of incubation (< stage 20). In older embryos (> stage 22), the vitelline and allantoic vessels have developed extensively and the in ovo manipulation of the embryo becomes exceedingly difficult. Therefore, in this study, we validate an ex ovo electroporation system, by which the time for performing electroporation can be extended up to at least day 7 of incubation. The application of this method will help to study gene function and regulation at later stages of development in the living chicken embryo.