Biological Specimen Preparation Research Articles

The Use of Gach Technique in Stabilizing Biological Specimens For X-Ray Microanalysis

An alternative SEM preparative technique is proposed for biological specimens in which cellular diffusible constituents may be retained that are otherwise lost during conventional specimen preparation involving critical point drying. The technique utilizes the copolymerization of glutaraldehyde with carbohy-drazide, and is designated “GACH”. Surface morphology with GACH preparations is as good as, or better than, that preserved using critical point drying. Bulk specimen preparation for elemental analysis has been limited heretofore to frozen-hydrated, freeze drying, freeze substitution, unfixed air dried, and critical point dried specimens. All such techniques offer particular advantages, but with certain limitations. The GACH technique is not being proposed as a superior routine replacement for present biological bulk specimen preparation methods, but rather as a viable alternative technique that allows both the retention of bound ions and acceptable surface morphology without elaborate instrumentation.

The Science of Biological Specimen Preparation for Microscopy and Microanalysis

The Science of Biological Specimen Preparation for Microscopy and Microanalysis

Utilization of aminoplastics as an alternative biological SEM specimen preparation technique

Utilization of aminoplastics as an alternative biological SEM specimen preparation technique

Ultramicrotomy and Ultracryotomy in Silicone Polymer and Elastomer Research

Traditionally, the soft resilient silicone polymer and elastomer systems have been thin-sectioned for electron microscopy employing methacrylate embedment techniques for hardening the material. often methacrylate infiltration causes the silicone material to swell--to an extent inversely proportional to the crosslink density of the polymer or elastomer. Therefore, a major difficulty encountered in the embedment of partially crosslinked silicones is the spatial distortion of the ultrastructure due to swelling. Using the method of ultracryotomy, however, the specimen is hardened by cooling below its glass transition temperature and sectioned, eliminating embedment artifacts. Christensen described application of the Sorvall frozen thin sectioner (PTS) to biological specimen preparation at about -75°C. Since silicone polymers exhibit extremely low glass transition temperatures (-125°C for poly(dimethylsiloxane)), they present a very unique challenge in this new area of ultracryotomy. Using the FTS unit on a Sorvall MT-2 ultramicrotome, silicone polymers have been successfully sectioned as thin as 500A in our laboratory.

Biological specimen preparation equipment

Biological specimen preparation equipment