Principal component analysis to identify genome-wide transcriptional variation caused by in ovo electroporation. This plot shows the variation between the samples; each dot represents the global gene expression of a single microarray. The greatest variation is measured on the x-axis, then the y- and z-axes, respectively. Wild-type VLM, VLMi and VLMg samples cluster together on the x-axis, indicating that there is little variation in the gene expression between these three conditions. VLMd, in which the regulatory gene Dmrt5 is exogenously expressed, clusters separately, indicating larger genome-wide variation between this sample and the others.