Part 1 Flashcards
The first and most critical step in histotechnology is
Fixation
A process that preserves tissues from decay, thereby preventing autolysis or putrefaction.
Fixation
If fixation is not adequate, these other processes that follow will be affected
Dehydration, Clearing, infilatration, Embedding, Microtomy and Staining
T/F: Fixation should be carried out as soon as possible after removal of the tissues (in the case of surgical pathology) or soon after death (in the case of autopsy) to prevent autolysis.
TRUE
This stabilize the fine structure, both inside and between cells, by making macromolecules resistant to dissolution by water and other liquids
Lysosomal enzymes
Primary goal of fixation
Preserve the morphologic and chemical integrity of the cell in as life-like a manner as possible
T/F: All vital cellular processes stop when the tissue is placed in a fixative.
TRUE
Second goal of fixation
To harden and protect the tissue from the trauma of further handling, so that it is easier to cut and process for microscopy
Results from tissue digestion by intracellular enzymes that are released when organelle membranes rupture.
Autolysis
brought about by microorganisms which may already be present in the specimen.
Bacterial Decomposition or putrefaction
Processes that must be prevented in fixation
Autolysis and putrefaction
Fixation in __ will initially cause slight swelling of tissue specimen
10% buffered formalin
Specimen may shrink or lose how many percent during processing?
20-30% of its volume
Leaving the tissue in water (a hypotonic solution) will cause the cell to
Swell
Leaving the tissue in a strong salt (hypertonic sol’n) will cause the cell to
Shrink
Cell structure also called as “suicide sac” that contains hydrolytic enzymes that are released when the integrity of the cell is destroyed
Lysosome
occurs due to the action of these hydrolytic enzymes
Postmortem decomposition (autolysis)
This method include heating, microwaving and cryo-preservation (freeze drying)
Physical Method
A type of physical method rarely used on tissue specimens, its application being confined to smears of microorganisms
Heat fixation
Physical method which can be regarded as a form of heat fixation, is now widely practiced in routine laboratories.
Microwave fixation
Physical method usually in the form of freeze drying, has some applications in histochemistry but is not usually applied to diagnostic tissue specimens.
Cyropreservation
Fixation method that is usually achieved by immersing the specimen in the fixative solution (immersion fixation) or, in the case of small animals or some whole organs such as a lung, by perfusing or injecting the vascular system with fixative (perfusion fixation)
Chemical Fixation
Can be used to vapor-fix freeze-dried tissues.
Paraformaldehyde and osmium tetroxide
Mechanism involved in fixation whereby the chemical constituent of the fixative is taken in and becomes part of the tissue by forming cross-links or molecular complexes and giving stability to the protein.
Additive fixation
