Histology is a specialty that consists of studying the structure of organic tissues under a microscope, whether human, animal or plant. In medicine, it contributes to the detection and diagnosis of certain pathologies, but also to numerous research works.

Histology is a branch of anatomy that focuses on the microscopic structure of the tissues and cells that make up an organism, in order to better understand and analyze their functioning. We could also speak of microscopic anatomy.

It is widely used by researchers, in particular by those who study the cellular mechanisms involved in inflammatory, genetic, degenerative, tumoral or other diseases. It also allows experiments to be carried out in vitro, on tissues cultured in the laboratory, instead of or before the launch of in vivo tests: observation of the consequences of pollution on the respiratory epithelium, of the effect of a drug active ingredient on a target tissue, a cosmetic product on the skin, etc.

Histology is used in many other scientific fields (animal, plant biology, etc.), in the food industry (for example to control the type of meat used in a prepared dish), but also in medicine, within the framework of various screening or diagnostic examinations. 

Before being able to study tissues under a microscope, the histologist prepares them according to a particular method, which makes it possible to chemically stop their natural degradation, to solidify them and then to cut them very finely, without damaging them. He then colors these histological sections before fixing them on the microscope slides. After all these steps, which require a few days, he will be able to observe all the structures of the tissue by transparency.

Histology is widely used in medicine, not by general practitioners and specialists whom the patient consults, but by anatomopathology laboratories to which medical samples are sent (smears, biopsies, etc.). 

Indeed, histology is one of the methods available to pathologists to identify the existence of possible abnormalities in a tissue or organ. Thanks to this method, they can precisely describe the samples they receive: presence of atypical cells, degeneration or unusual organization of the tissues, etc.

If cancer is suspected, they can confirm (or not) the diagnosis, then decide on the type of lesion, its grade and its evolution. Histological tissue analysis is even useful when there is no doubt about the existence of a tumor, since the details provided make it possible to guide the therapeutic strategy.

Surgeons may also have recourse to a pathologist during and after an operation. When they remove a tumor, for example, they remove a margin around it, to limit the risk of leaving cancer cells in place. But, as a precaution, they also send this resection for analysis, to verify that the entire lesion is contained therein.

Finally, all the histological sections being archived by the laboratories, they can be re-analyzed if necessary several months or years after the initial diagnosis. This happens in particular when doctors observe an unexpected evolution of the pathology and seek to understand it, or for the needs of medical research.

Depending on the case, the pathologist will do the preparation himself or ask a histologist to take care of it.

Not quite. Pathologists are physicians. They have a Bac + 8 level, with a doctorate in medicine or a diploma of specialized studies (DES) in medical biology or in pathological anatomy and cytology. They have expertise in histology, but also in other methods of observing organs and tissues: macroscopic analyzes, with the naked eye, of organs taken during surgical operations (prostate, etc.), microscopic analyzes of samples which, because an answer must be given before the end of the operation, do not have time to be processed for histology, etc.

Working in hospitals or in medical analysis laboratories, these doctors are able to make their own histological sections or can delegate this task to histologists. The latter master all the usual steps of this preparation, but also all the staining techniques making it possible to highlight a particular cell element, if this is specifically desired.

There are many histologists in research laboratories. Some have a medical degree, but it is not necessarily necessary. It depends on the topics they are working on.

As explained above, some are doctors, others have more of a Bac + 5 training, with an engineering degree or a master’s degree in biology, biochemistry, molecular and cellular biology, biotechnology… They put their expertise at the service of the sector in which they work.

The patient never directly meets the person who will analyze his tissue samples. It is his general practitioner or specialist who will have recourse to him, as part of a screening or to confirm a diagnosis.

The report of the histological examination will often be very technical and returned to the doctor, who will then be responsible for clearly explaining it to his patient.