Formalin Neutral buffered 10% ready to use:
Formaldehyde (or Fòrmica aldehyde, name IUPAC: Metanale) is the simplest of aldehydes. Its chemical formula is CH2O, its CAS number is 50-00-0.
The 10% buffered formalin (4% formaldehyde) is one of the most used fixatives because it does not preclude any examination in the Histologic field.
The mechanism of action is the formation of methylene bridges by the active form methylene glycol.
It forms methylenic covalent bonds and achieves intra-and intermolecular cross-linking between the adjacent groups of: lysine, arginine, tyrosine, Asparigina, histidine, glutamine, serine and sugars.
Fixation with formalin:
It consists of subjecting the tissue to the histological examination to chemical agents and sometimes to physical agents that quickly denature the proteins, binding themselves to the numerous functional groups and which make the other constituents insoluble for the subsequent phases of Dehydration, inclusion and coloring. The best fixatives are those that precipitate the proteins in the finer form, preferably in ultra-microscopic attachments, so that the morphology is not modified. All fixatives must be prepared as isotonic solutions and PH 7.4, to prevent phenomena of collapse or swelling of the samples, linked to osmotic stresses.
Minimizes tissue degradation, resulting in tissue removal from its vital environment, as a result of temperature and pH variation;
- It protects from the action of microorganisms that, after removing the tissue, invade the biological material, nourishing the structures no longer able to protect themselves;
- It allows the preparation to withstand the physical and chemical stresses inherent in the subsequent phases of dehydration, inclusion and sectioning.