ABSTRACT
Techniques such as Southern, western and northern blotting as well as the polymerase chain reaction-based methods can be applied to whole tissue extracts. However, unlike cultured cells, tissue samples are often a heterogeneous mix of cell types. Hence, a possible drawback of using these methodologies is the inability to discriminate between the cell types being analysed. This is the major strength of histological techniques such as immunostaining and insitu hybridisation, which can be used to demonstrate the expression of antigens and nucleic acids, respectively, at the cellular level, and their associations with particular cells. Cells grown in culture need to be put onto glass slides in order for them to be processed for exploratory techniques such as in situ hybridisation or immunostaining. Tissue samples are normally available in two forms: fixed paraffin embedded and freshly (snap) frozen.
