Figure 1. Oligonucleotide primers used for Section-RT-PCR (upper). Section-RT-PCR of rat maxillary periodontium in weeks 3 (W3) and 4 (W4) (lower). Gene expression of MMP-8, MMP-13, and GAPDH is identified. Negative controls (non-RT) do not produce bands visible on gels. Positive controls (total RNA of embryonic rat limbs) show the corresponding bands.