On-block UV light polymerization of LR gold-embedded flat-mounted tissue using low temperature modules

A problem associated with low temperature embedding is due to the fact that suitable resins have to be polymerized under oxygen-free atmosphere, thus making the complete filling and tight sealing of vials or capsules essential. Particularly with thin tissue sections or retinal flat-mounts it is rather difficult to obtain flat-embedded specimens under these conditions. To overcome this problem, we have designed a low temperature module (LTM) that allows the polymerization of flat tissue probes on faced resin blocks using UV light, thus instantly creating ready specimens with an almost planar surface. To test the device, vibratome sections of the rat superior colliculus were embedded in LR Gold and UV-cured in LTMs. Electron microscopy revealed a good preservation of the fine structure. The new UV light polymerization technique proved to be highly suitable to obtain ultrathin sections being cut parallel to the surface of the embedded material, an advantageous feature for applications which necessitate the examination of specifically oriented or laminated structures. Detailed and dimensioned drawings of the LTM can be downloaded as a PDF file at: http://www.uni-leipzig.de/-vetana.