The Rayleigh resolution of a zone plate TXM system is determined by approximately the size of the outermost smallest zone width, and thus, is tightly connected to advancements in the lithographic fabrication process of zone plates, currently allowing hard X-ray microscopy resolutions well below 50 nm.

Whereas SR-based zone-plate TXM setups are frequently used in 2D, as well as in 3D when combined with Rapamycin a rotation stage for tomography, it was not until recently that a first desktop TXM CT system was implemented [21], which is operated with a commercial X-ray tube. An initial TXM CT measurement performed on this system provided a 3D reconstruction of an osteocyte lacunae and radiating canaliculi of a tibial trabecula in the mouse [22]. Although the spatial resolution of the system in 2D has been reported to be below 50 nm [22], canaliculi in the 3D reconstructions were interrupted. Therefore, further

refinements to this technology are needed in order to accurately model the canaliculi in 3D. Higher GDC-0199 ic50 spatial resolutions can be achieved using electrons instead of X-rays, where the resolution of an electron microscope increases in a manner that is inversely proportional to the square root of the applied voltage, and is typically in the nanometer range. TEM has been extensively used to investigate in 2D the ultrastructure of osteoblasts and osteocytes including their dendritic processes.

The morphology of osteocytes and their processes were further characterized in 3D by successive serial sectioning and TEM imaging [23]. More recently, Kamioka et al. adopted TEM computed tomography (TEM CT) on an ultra-high voltage electron microscope, where silver-stained osteocytes in 3-μm chick calvaria sections were Interleukin-3 receptor assessed at an accelerating voltage of 2 MeV and at a nominal resolution of 16 nm [24]. Prominent silver deposition for young osteocytes, which has been observed in their nuclei and in the pericellular space, was used to segment the cell nuclei, cell bodies, and the osteocyte processes (Fig. 1B). Kamioka and colleagues found that the surface of the osteocyte network was irregular and that the size and shape of the cell processes varied significantly. Besides the demanding sample preparation, a major problem of TEM is the fact that for a dense material like bone, even at ultra-high voltages, the maximal sample thickness that can be penetrated by electrons is only a few μm due to strong scattering and absorption for thicker specimens.