This protocol describes a basic method for in vivo electroporation in the nervous system of embryonic mice. Delivery of electric pulses following microinjection of DNA into the brain ventricle or the spinal cord central canal enables efficient transfection of genes into the nervous system. Transfection is facilitated by forceps-type electrodes, which hold the uterus and/or the yolk sac containing the embryo. More than ten embryos in a single pregnant mouse can be operated on within 30 min. More than 90% of operated embryos survive and more than 90% of these survivors express the transfected genes appropriately. Gene expression in neurons persists for a long time, even at postnatal stages, after electroporation. Thus, this method could be used to analyze roles of genes not only in embryonic development but also in higher order function of the nervous system, such as learning.

Note: In the version of this article initially published online, several instances of the phrase in vivo were incorrectly substituted with in ovo. When the article was first corrected, not all instances were changed appropriately. These errors have been corrected in all versions of the article. In addition, on p. 1557 the first line of the Troubleshooting section should read “Steps 6A(i)-(iv) and 6B(i)-(iv)…” rather than “Steps 6A(i)–(iv) and 6B(ix)–(xii)…”