Figure 1A-(left)-Section of normal rat molar (it's tough to make out on this scan, but the striations are tubules conducting fluorescent material from the pulp to the enamel)

Figure 1B-(right)-Section of rat molar showing the effects of bradykinin, which causes red material beneath the plaque to penetrate the tooth structure as far as the pulp (via the same tubules as seen in the left figure).