Histology

The histology (of the Greek ἱστός) is the Branche of the Biologie which studies the fabrics, halfway between the Cytologie and the Anatomie. The purpose of it is to explore the composition, the structure, the renewal of fabrics, as well as the cellular exchanges in their center.

History

It is Italian Marcello Malpighi, professor of Médecine to Bologna and Pisa which is regarded as its founder at the 17th century, using the Microscope then recently invented. It is however with Bichat that we owe the concept of fabric, one century later.
The cellular theory appears as for it only in 1838, introduced by Matthias Jakob Schleiden (1804-1881) and Theodor Schwann. According to Virchow, any cell comes from a preexistent cell.

Histological techniques

Taking away

In the medical environment, the taking away are carried out in private clinic or hospital. They are carried out by surgeons.
  • One distinguishes four major categories of taking away:
    • smears: scraping (of the cervix…),
    • biopsies: fragments of fabric or body,
    • bodies in integrality,
    • liquids of épanchement various (pleural, ascite, pericardial, etc).
There exist also techniques of taking away more sophisticated: by excision, puncture, or microdissection.

Conservation

In order to preserve the sample in a state nearest possible to the state in-vivo, two means of conservation can be used:
  • the congelation, used for the taking away in operating room whose diagnosis must be known quickly (extemporané examination);
  • fixing by chemicals like the Formol, which causes to polymerize proteins and, in certain cases, lipids present in the body. This technique is used for the histological cuts " long durées" after paraffin inclusion.

Thinning

The bodies, too large to let pass the light necessary to optical microscopy, must still be cut out in plates. For that, one coats them in paraffin or a resin, according to the desired thickness of the cut. One distinguishes several types of cut according to the method of conservation and thinning followed:

The cuts of 0,05 μm will be analyzed in electronic microscopy while the others will be observed in optical microscopy.

Coloring

In order to distinguish various fabrics, one can have recourse to different dye S. Among the various techniques of coloring, Hemateine-Eosine allows a coloring blue of the core and pink of the cytoplasm.

See too

Tissue morphology:

Embryonic fabrics:

Botany:

External bonds

  • Course of first year of medicine of histology, at the University Rene Descartes - Paris V: http://lhec.teso.net/enseignements/p1/polyp1/tdm.html
  • Course of P1 of Nice (tissue morphology): http://homepage.mac.com/danielbalas/teaching.html

Simple: Histology

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