Here we present a protocol to increase chimera production without the use of new equipment. A simple orientation change of the embryo for injection can increase the number of embryos produced, and potentially reduce the timeline to germline transmission.
Mouse fertilized eggs and early stage embryos are protected by the zona pellucida, a glycoprotein matrix that forms a barrier against gene delivery. This article describes a protocol for perforating the zona with a laser to transduce embryonic cells with lentiviral vectors and to create transgenic mice.