In situ hybridization: optimization of the techniques for collecting and fixing the specimens

An overview is presented concerning the different protocols for collecting and fixing the specimens for in situ hybridization analysis. Particular attention is devoted to the problem of avoiding the tissue RNA degradation due to the ubiquitous and rather resistant RNases. The choice of the final protocol largely depends on a compromise between the need to maintain morphological details, the care to avoid loss of the target nucleic acids and the capability of the probe to diffuse within the specimen.