MINERAL PHASE MICROSTRUCTURE IN TEETH OF THE SHORT SPINED SEA URCHIN (Lytechinus variegatus) STUDIED WITH X-RAY PHASE CONTRAST IMAGING AND WITH ABSORPTION MICROTOMOGRAPHY

摘要

X-ray absorption microtomography, a high resolution variant of medical “CT”, and synchrotron x-ray phase contrast imaging reveal the distribution of mineral within teeth of the sea urchin Lytechinus variegatus. Data from these imaging modalities on intact teeth are compared with histochemically stained thin sections observed with transmission optical microscopy. Because these teeth grow continuously, the complex variation of attenuation from aboral to incisal end shows how the sea urchin increases mineralization to produce a hard, self-sharpening cutting edge. The phase contrast radiographs appear to show the calcite crystal morphology with greater sensitivity, at least in some portions of the tooth.