Fig 4.

Average element concentrations in the four samples (A–D) in the proliferative (left) and hypertrophic (right) zones over areas 350–550 µm (left) and 650–950 µm (right) as indicated in Fig. 3. These areas are selected because they are parts of, respectively, the proliferative and hypertrophic zones in all animals. The only exception is for the concentrations of Cl and K in the hypertrophic zones in animals C and D. Because these elements develop steep gradients towards the mineralized area (Fig. 3C,D), they are averaged over 105–107 µm (animal C) and 98–100 µm (animal D).