Histology strategies
Histology techniques involve rigorous processes.
In major cases, the tissues are fixed immediately after dissection: the fixation allows the conservation of the structural elements of the tissues.
The inclusion step consists of the embedding of the tissue to serve as a support for the sectioning. The embedding way determines the suitable material for the cut and will be function of the desired thickness of sections. For example, microtomy will be preferred to obtain very thin sections around 5 μm, while the vibratome will allow very thick sections to be obtained up to 300 μm.
This information can also be obtained from cell lines / spheroids / organoids pelletized, fixed and then embedded in paraffin or in OCT.
It is also possible to do histology from non-fixed material. Indeed, the tissues can directly be frozen, embedded and cut without prior fixation if this is desired for the preservation of certain elements such as RNA or other specific molecules.
Finally, there is a technique of "living" organ sections culture in order to follow the development of the tissue in vitro. To do this, the non-fixed organ is included in agarose + culture medium and cut with a vibratome. The sections obtained are cultured for several hours / days. Stainings can then be carried out at different times and “imaged” by “lived” microscopy or after fixing the sections mounted on slides.