Because of the high accessibility to developing embryos, avian embryos (chicken and quail) have long been used as a good model animal to study embryogenesis in vertebrates, especially amniotes (reviewed in Wolpert, 2004). The techniques used for classical avian embryology included tissue transplantations, tissue ablations, and cell-labeling by vital dye. At the end of the last century, the in ovo electropora tion technique was developed by Nakamura and his colleagues, and this modern method opened a way to study the roles of developmental genes directly in living embryos (Funahashi et al., 1999) reviewed in (Nakamura et al., 2004; Yasuda et al., 2000; Yasugi and Nakamura, 2000). This powerful technique allows us to introduce genes (DNA, RNA, morpholino) into embryos in a tissue-specific way by targeting a restricted area of embryonic tissues. Thus, the electroporation technique using chickens has provided numerous novel insights into the understanding of early development in vertebrates, making the chicken a unique model animal. One of few shortfalls of the original technique has been that expression of electroporated genes does not persist for a long period of time probably because the introduced plasmids, which are not integrated into the genome, degrade or become diluted as embryonic cells undergo massive proliferation. Although a spontaneous genomic integration of electroporated genes could occur, this incidence must be extremely low. Since in most cases the electroporation is performed at embryonic day 1∼2 (E1∼E2), the short life of introduced genes hampers the analysis of the effects by introduced genes at late stages, i.e., from E5 onward, when a variety of organogenesis proceeds. At these late stages, the electroporation is difficult to perform because the embryo is much less accessible.
All Science Journal Classification (ASJC) codes
- Materials Science(all)