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39, 40,
41, 43,
44.
PRINCIPLE OF THE TEST.
Examination for polarizable crystals.
SPECIMEN REQUIRED.
All human tissue excised at surgery, outpatient clinics, and postmortems,
fresh or in fixative, along with a filled-out Tissue Examination Form
(U. S. Standard Form 515, USSF515).
REAGENTS, INSTRUMENTATION.
Microscope. Polarizing discs.
STEP-BY-STEP DESCRIPTION.
1. Scan for Crystals.
1.1. Find one polarizing disc and place over the light source.
1.2. Switch the microscope's polarizing disc into place by turning
the analyzer control (see Figure A) until "1" is seen.
1.3. On 45X (high dry) rotate the disk over the light source until
the background is maximally dark.
1.4. Scan for crystals at 45X. They appear bright on a dark background.
Sodium Urate crystals are small and needle-like. Calcium phrophosphate
crystals vary in appearance.
2. Determine Birefringence.
2.1. Set up the polarizing filters as described above.
2.2. Find the First-order red plate. It is labeled "Quarz Rot 1''
and looks like a small black frying pan.
2.3. Place the First-order red plate over the polarizing disk.
Turn the First-order red plate, without turning the polarizing
disk, until the background seen in the microscope is red.
2.4. Crystals are evaluated when
perpendicular or parallel to the axis of the First-order red
plate by the crystal's color.
REFERENCE.
1. Henry JB, ed.
Clinical Diagnosis and Management by Laboratory Methods.
Twentieth Edition.
Philadelphia: W.B. Saunders Company. 2001;:.
ISBN: 0721688640, 1512 pages.
2. Henry JB, ed.
Clinical Diagnosis and Management by Laboratory Methods.
Nineteenth Edition.
1996;:469-470.