Surg Path Flashcards
Most routinely and commonly used fixative for tissues;
WITH Buffer component: Disodium hydrogen phosphate (Na2HPO4)
and monosodium phosphate (NaH2PO4)
10% Neutral Buffered Formalin
• Ways to speed up fixation:
→ Heat - Add concentrated formalin and then heat it at 60°C in
a water bath
→ Agitation - Usually done in smears with alcohol being the
fixative
Automated Tissue Processor principle
Displacement
Reagent for Dehydration
Ethanol since it is miscible w water
done by immersing specimens in
increasing concentrations of ethanol until pure, water-free alcohol is reached
Dehydration
wax and ethanol are immiscible so intermediate solvent is used para maging mixed
CHLOROFORM
Typical clearing agents
xylene;
chloroform;
toluene
benzene
Melting point paraffin
54-58° Celsius
rotary-type mictorome
commonly used in the
histopathology laboratory
Ideal thickness of tissue section:
3-4 microns
in sectioning;
Temp of water bath must be set ___
10ºC below the melting point of the paraffin
wax to prevent the melting of paraffin
Why is paraffin removed
to enable water-soluble dyes to enter;
40-50 mins in 100 deg celsius
Mounting done because Refracting index of the medium should be close to the average refractive index of the tissues
COMMON medium:
Entellan
Staining Principle: ___
• The sections are overstained with dye, and the excess stain is
removed using ___, or decolorizer
• The sections are then neutralized with ___ (blueing
agent)
Regressive Staining
Acid alcohol;
Ammonia water
For quick processing of fresh tissues (30 minutes)
NO PARAFFIN;
pero remaining specimen processed routinely
Frozen section;
Cryostat microtome used where embedding media is gel, temp is -20 deg C and liquid nitrogen is used to harden gel
