= (2.8, 4.0) conditions (Figure , flat geometry). All {kl0} reflections are indeed overexpressed compared to the simulated pattern, suggesting their preferential exposure. When using a sample holder geometry minimizing preferential orientation (Figure , capillary geometry in transmission mode under synchrotron radiation), the relative intensities expected from the tabulated structure are recovered. These results are consistent with anisotropic growth along the c axis that corresponds to the direction of hydroxyapatite channels. Accordingly, SEM (Figure )