Tissue ProcessingTissue Processing

Tissue Processing

Tissue Processing, In order to obtain a thin section from a tissue sample received in the laboratory, it is necessary to obtain an adequate degree of stiffness in the tissue. So that it can be easily cut with the help of blade or knife. Moisture in the tissue can be due to the water found in the cells of the tissue or the water found between the cells. This water is removed and replaced with a solid material such as Paraffin Wax. Which causes the tissue to become stiff when cold. All this process is completed in the following three steps.

It is important to label the specimen properly before tissue processing. Tissue processing is a lengthy process that takes about twenty-four hours. Specimens are placed in special mesh jars and these jars are transferred from one chemical to another chemical during tissue processing.

Tissue Processing can be done in two ways.

  • Manually
  • Automatically


In this step, water in the tissue is removed and replaced with a chemical that is capable of dissolving in water. Chemicals that are used for dehydration are called dehydrating. Alcohol is usually used for dehydration. And for this purpose the strength of alcohol is gradually increased. First 70% alcohol is used. Then 90% and finally 100% pure alcohol is used. If the tissue sample to be received is very delicate, 50% alcohol is used first. The length of time the sample remains in the alcohol depends on the size of the sample. Usually kept in a jar of alcohol for one to two hours. And if the container with alcohol is shaken, this time can be reduced.

Tissue Processing
Tissue Processing


In this step, the alcohol in the tissue is removed and replaced with a chemical. The chemical in which alcohol is soluble is called Agent. This chemical has dual properties. It is not only soluble in alcohol but also soluble in wax. Usually, a small sample of Xylene tissue is placed in Xylene for one to one and a half hours. While the larger sample takes two to four hours to clear.


In this step, after clearing, the tissue is embedded in wax. Wax has a typical melting point of about 54-60. The tissue sample is kept in a jar of wax for some time. The amount of wax should be 25-30 times the size of the tissue. Usually two jars of wax are used. This wax replaces the xylene in the tissue and solidifies when cooled. Thus the tissue is internally supported. And the tissue hardens.

Names of Dehydrating Agent:

  • Alcohol, (Methanol, Ethanol)
  • Aceton
  • Di oxane
  • Isopropanol

Names of Clearing Agent:

  • Xylene, Toluene
  • Benzene, Chloroform
  • Petrol
  • Cedar Wood Oil
  • Carbon Tetrachloride

Names of Impregnation Media:

  • Paraffin Wax
  • Carbo Wax
  • Celloidin
  • Para Plast
  • L.V.N (Low Viscosity Nitro Cellulose)

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