Page 29 - Textbook of Pathology, 6th Edition

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TABLE 2.1: Contd...
Stain Component/Tissue Dyes Interpretation
F. NEURAL TISSUES
21. Luxol fast blue Myelin Luxol fast blue, Myelin: blue/green
cresyl violet Cells: violet/pink CHAPTER 2
22. Bielschowsky’s silver Axons Silver nitrate Axon and neurofibrils: black
G. PIGMENTS AND MINERALS
23. Perl’s Prussian blue Haemosiderin, iron Potassium ferrocyanide Ferric iron: blue
Nuclei: red
24. Masson-Fontana Melanin, argentaffin cells Silver nitrate Melanin, argentaffin,
chromaffin, lipofuscin: black
Nuclei: red
25. Alizarin red S Calcium Alizarin red S Calcium deposits: orange red
26. von Kossa Mineralised bone Silver nitrate, Mineralised bone: black
safranin O Osteoid: red
27. Rubeanic acid Copper Rubeanic acid Copper: greenish-black
Nuclei: pale red
28. Pigment extraction Removal of formalin pig- Alcoholic picric acid Formalin pigment/malarial
ment and malarial pigment pigment: removed Techniques for the Study of Pathology
29. Grimelius’ Argyrophil cells Silver nitrate Argyrophil granules: brown-black
H. PROTEINS AND NUCLEIC ACIDS
30. Feulgen reaction DNA Potassium metabisulphite DNA: red purple
Cytoplasm: green
31. Methyl green-pyronin DNA, RNA Methyl green, DNA: green-blue
pyronin-Y RNA: red

ENZYME HISTOCHEMISTRY LIGHT MICROSCOPY. The usual type of microscope used
in clinical laboratories is called light microscope. In general,
Enzyme histochemical techniques require fresh tissues for there are two types of light microscopes:
cryostat section and cannot be applied to paraffin-embedded Simple microscope. This is a simple hand magnifying lens.
sections or formalin-fixed tissues since enzymes are damaged The magnification power of hand lens is from 2x to 200x.
rapidly. Currently, enzyme histochemistry has limited Compound microscope. This has a battery of lenses which
diagnostic applications and not so popular, partly due to are fitted in a complex instrument. One type of lens remains
requirement of fresh tissues and complex technique, and near the object (objective lens) and another type of lens near
partly due to relative lack of specificity of reaction in many the observer’s eye (eye piece lens). The eyepiece and objective
cases, and hence have been largely superseded by immuno- lenses have different magnification. The compound
histochemical procedures and molecular pathology microscope can be monocular having single eyepiece or
techniques. binocular which has two eyepieces (Fig. 2.5). Multi-headed
Presently, some of common applications of enzyme microscopes are used as an aid to teaching and for
histochemistry in diagnostic pathology are in demonstration demonstration purposes.
of muscle related enzymes (ATPase) in myopathies,
acetylcholinesterase in diagnosis of Hirschsprung’s disease, VARIANTS OF LIGHT MICROSCOPY. Besides the light
choloroacetate esterase for identification of myeloid cells and microscopes, other modifications for special purposes in the
mast cells, DOPA reaction for tyrosinase activity in clinical laboratories are as under:
melanocytes, endogenous dehydrogenase (requiring Dark ground illumination (DGI). This method is used for
nitroblue tetrazolium or NBT) for viability of cardiac muscle, examination of unstained living microorganisms e.g.
and acid and alkaline phosphatases. Treponema pallidum. The microorganisms are illuminated by
an oblique ray of light which does not pass through the
microorganism. The condenser is blackened in the centre and
BASIC MICROSCOPY
light passes through its periphery illuminating the living
microorganism on a glass slide.
Microscope is the basic tool of the pathologist just as is the
stethoscope for the physician and speculum for gynaecologist. Polarising microscope. This method is used for demonstration
It is an instrument which produces greatly enlarged images of birefringence e.g. amyloid, foreign body, hair etc. The light
of minute objects. is made plane polarised. After passing through a disc, the