Figure 2From: Validation of reference genes for quantitative RT-PCR studies in porcine oocytes and preimplantation embryosOptimal number of reference genes. Pair wise variation of normalization factors after successive inclusion of less stable genes determined the optimal number of reference genes. On the left-most side is the pair wise variation when the number of genes is enlarged from 2 to 3 (V2/3). Stepwise inclusion of less stable genes generates the next data points. Inclusion of a 4th gene has a significant effect on the normalization factors. Inclusion of a 5th, 6th, or 7th gene has a negative effect on the pair wise variation value and reflects the average expression stability M of these genes.Back to article page