Methods for introducing morpholinos into the chicken embryo

The use of antisense morpholino oligos to inhibit the translation of a target transcript has been applied recently to studies of the chicken embryo. In contrast to other developmental systems such as in frog, sea urchin, and zebrafish that permit the direct microinjection of morpholinos into a blastomere, square pulse electroporation is used to introduce fluorescently tagged morpholinos into specific populations of chick embryo cells in ovo. This article reviews the methods that have proven successful, the types of controls that are necessary when performing knockdowns of gene expression in the chick embryo, and discusses the limitations of the current technique, as well as directions for further research. (C) 2003 Wiley-Liss, Inc.