Irradiation damage to frog inner ear during synchrotron radiation tomographic investigation

Unexpectedly severe radiation damage, showing up through deformation of the saccule, was encountered during a synchrotron radiation high-resolution (700 nm pixel size) tomographic observation of an inner ear, fixed in a formaldehyde solution, of the frog Rana esculenta. The visible displacement of the edge of the otoconia-filled part of the saccule amounted to about 100 μm after an irradiation with 20.5 keV X-ray photons corresponding to a dose of 1.5 kGy for the protein matrix. The close-knit coexistence of organic and mineral components in the biological tissue may be linked to the dramatic increase of radiation dosage sensitivity.