  Joint tissues consist of trabecular and cortical bone as well as calcified
and hyaline cartilage, which presents a challenge for hard X-ray-based
visualization on the sub-cellular level due to the wide range of local X-ray
absorption values. The density of the calcified tissues requires rather high
photon energy, which often leads to insufficient contrast within the cartilage
and impedes the visualization of individual biological cells. Decalcification
of the tissues reduces the total and local X-ray absorption values and allows
for selecting a lower photon energy. Further contrast enhancement can be
achieved by ethanol fixation and paraffin tissue embedding. In this study, we
(i) searched for an appropriate visualization method to investigate lesions
generated by a laser osteotome and (ii) visualized a decalcified porcine joint
after ethanol fixation and subsequent paraffin embedding using laboratory- and
synchrotron radiation-based microtomography. The experiments at the ANATOMIX
beamline of Synchrotron SOLEIL were performed in off-axis scan mode with a
pixel size of 1.3 um. Individual cells in all layers of the joint could be made
visible and the effect of ethanol fixation and paraffin embedding demonstrated.
