In vivo electroporation of E1 chick embryos.

In ovo electroporation of chick embryos at ages ≥ E2 is simple to conduct and widely used to manipulate gene function. However, in ovo electroporation at early E1 stages has so far been unsuccessful because of unacceptable levels of tissue damage and embryonic lethality. Early E1 manipulations in the chick have therefore relied on in vitro electroporation, posing problems for morphogenetic studies in which the long-term preservation (>24 h) of three-dimensional tissue organization is critical. This article describes a simple technique for in vivo electroporation of E1 embryos as young as Hamburger-Hamilton stage 4 (HH4). It uses thin microelectrodes and low voltages, which permit precise localization of gene misexpression while causing minimal tissue damage and embryonic lethality. Critically, it does not depend on the presence of a lumen for DNA injections and can easily be adapted for a wide variety of tissues.