What does tissue processing mean?

Tissue processing is the technique by which fixed tissues are made suitable for embedding within a supportive medium such as paraffin, and consists of three sequential steps: dehydration, clearing, and infiltration.

What is Histotechniques?

Histotechnique is a term that describes the processes involved in producing a microscopic slide from specimens examined in the pathology laboratory.

Why is tissue processing done?

1. DEFINITION : Tissue processing: The aim of tissue processing is to embed the tissue in a solid medium firm enough to support the tissue and give it sufficient rigidity to enable thin sections to be cut, and yet soft enough not to damage the knife or tissue.

What is processing in pathology?

“Tissue processing” describes the steps required to take an animal or human tissue from fixation to the state where it is completely infiltrated with a suitable histological wax and can be embedded ready for section cutting on the microtome.

What is unfixed tissue?

Any unfixed tissue or organ (other than intact skin) from a human (living or dead). Human cell lines are considered OPIM if they can or do carry bloodborne pathogens. Some cell lines have been tested and certified by the suppliers to be free of bloodborne pathogens.

What is the most important step in tissue processing?

Fixation of tissues is the most crucial step in the preparation of tissue for observation in the transmission electron microscope. Fixation consists of two steps: cessation of normal life functions in the tissue (killing) and stabilization of the structure of the tissue (preservation).

What is the main principle of tissue processing?

Principles of tissue processing. Tissue processing is designed to remove all extractable water from the tissue, replacing it with a support medium that provides sufficient rigidity to enable sectioning of the tissue without parenchymal damage or distortion.

What are the methods of tissue processing?

The three most commonly employed means of tissue processing are routine manual method, rapid manual method and the microwave method. Each of these methods is unique with their own advantages and disadvantages. Routine manual tissue processing has been the most commonly employed method for the past 100 years.

What is the difference between microtome and microtomy?

Microtome is an instrument with the help of which sections of tissues are cut and the process of cutting thin sections is known as Microtomy. The thickness of sections produced during microtomy may be between fractions of 50-100 nm, in ultramicrotomy, to several 100 microns.

What is microtomy and its types?

A microtome is a specialized precision cutting instrument, which accurately and repeatedly slices sections from a block of embedded tissue. Different kinds of microtomes are used to section paraffin and plastic embedded tissues (Figs. 4a–4c) as well as the specialized microtomes used to section frozen tissues (Fig.

What are common problems during microtomy?

Ribbon will not form

  • Paraffin too hard; needs to be stickier.
  • Room/block too cold/hot.
  • Sections too thick.
  • Cannot seem to anchor the ribbon.
  • Angle of knife clearance is too small.
  • Blade may be caked and dirty.
  • Something in microtome not clamped down securely.

Why is hydration important in tissue processing?

Dehydration is simply the removal of water from aqueous-fixed tissue. Since most fixatives are aqueous, this step is necessary to prepare the tissue for embedding in non-aqueous media like paraffin.

What is unfixed tissue preparation?

A quick, simple protocol is described for the preparation of tissue for electron immunocytochemistry without the use of fixatives or deleterious solvents. Fresh, normal human colon was rapidly dehydrated in ethanediol (ethylene glycol) then embedded directly in low-acid glycol methacrylate.

What’s considered Opim?

Other potentially infectious materials (OPIM) means: (1) The following human body fluids: semen, vaginal secretions, cerebrospinal fluid, synovial fluid, pleural fluid, pericardial fluid, peritoneal fluid, amniotic fluid, saliva in dental procedures, any body fluid that is visibly contaminated with blood, and all body …

What are some of the faults encountered during tissue processing?

Faults in Processing

Brittle or hard tissue Drying out of tissue before actual fixation
Failure to give special handling of tissues when treated with routine processing methods
Clearing agent turns milky as soon as tissue is placed in it Water not completely removed due to incomplete dehydration

What is Microtomy or ultra Microtomy?

Microtome is a piece of equipment that cuts very thin slices. Ultramicrotomy is a type of microtome that cuts extremely thin slices of plant and animal tissues. Selection of the technique depends on how thin the specimen should be for observation.

What is tissue processing?

Tissue processing ” describes the steps required to take animal or human tissue from fixation to the state where it is completely infiltrated with a suitable histological wax and can be embedded ready for section cutting on the microtome. Principles of Tissue Processing

What is involved in the first stage of tissue processing?

The first stage of processing is the removal of ‘free’ unbound water and aqueous fixatives from the tissue components. Many dehydrating reagents are hydrophilic and interact with the water molecules in the tissue by hydrogen bonding. Other reagents affect dehydration by repeated dilution of the aqueous tissue fluids.

What determines the turn-around time for tissue processing?

The laboratory’s desired turn-around time should dictate the how long the tissue is fixed and processed. Put the following tissue types/sizes in order of time required to process. Begin with tissue that requires the LEAST amount of processing time and fin…

How to validate new tissue processing programs?

2. 8. 3. To validate new processing programs, laboratories should run tissue samples of the same size, thickness and fixation induplicate. Reagents on the processor should be comparable, example all fresh reagents. Process, embed cut, and stain slides at thesame time and evaluate the quality of the blocks, example firmness, and ease of cutting.