2. What is
histochemistry?
It is the study of qualitative identification &
quantitative assessment of chemical
groupings within cells and tissues.
Histochemical techniques are based on
precise chemical rationales for their ability to
identify or stain different biochemical
substances.
Visualizing Chemicals and Enzymes in
Tissue.
3. Based on chemical reactions between
cell components and stains.
The end products of the reaction are
permanent, colored precipitates that
can be viewed under the microscope.
There are stains specific to each
component of the cell, based on the
basic or acidic nature of the dye.
10. Histochemical study of teeth
and bone
Simultaneous fixation and decalcification with
formaldehyde or gluteraldehyde and EDTA
(ethylenediaminetetraacetic acid) for light and
electron microscopic histochemistry.
Recently techniques have been developed for
sectioning freeze-dried, undecalcified tissues.
(eg: for studying DC).
Bone- deproteinization with conc. Hydrazine.
11. Specific histochemical methods
Carbohydrates- PAS
Proteoglycans- Toluidine blue, Azure A, Alcian
blue.
Proteins- Dinitrofluorobenzene, Ninhydrin or
Ferric ferricyanide
Lipids- Sudan dyes (Sudan black- phospholipids)
Enzymes (For eg-Phosphatases- Gomori
method)
12. Immunohistochemistry
Immunohistochemistry takes advantage of
antigen-antibody affinity through its ability to
identify and localize proteins of interest via
detection with labelled conjugates (fluorescent
dyes).
13.
14. Enzyme Histochemistry
The techniques of enzyme histochemistry, which relate
structure and function, can be used to locate many enzymes,
including acid phosphatase, dehydrogenases, and
peroxidases.
Enzymes indicates what is happening in the tissue
15. Histochemistry of Oral hard
tissues
Carbohydrates(PAS)
Proteins (dinitrofluorobenzene, ninhydrin or
ferric ferricyanide)
Lipids(Sudan dyes)
16. Enzyme histochemistry
Alkaline phosphatase- absorption
Adenosine triphosphatase- pre absorptive
ameloblasts
Acid phosphatase- resorption
Esterase- matrix of bone and dentin
Aminopeptidase- human osteoclasts
Cytochrome oxidase- oxidation (osteoblasts,
osteoclasts)
Succinate dehydrogenase- osteoclasts
17. Histochemistry of oral soft tissues
Polysaccharides
Proteins
Lipids
Mucins(PAS for neutral mucins & alcian blue
for acid mucins)