This document provides an introduction to the field of histochemistry. It discusses the historical origins and key figures in histochemistry. It then outlines the main components of tissues that can be studied using histochemistry techniques, including epithelial, connective, muscle and nerve tissues. Finally, it discusses various histochemistry staining methods and considerations for tissue processing and quality control.

1. Introduction to Histochemistry
Kwabena Owusu Danquah (PhD)
Sept 2017

2. Learning Outcomes
- Narrate historical journey in histochemistry
- Appreciate physico-chemical nature of cells/ tissues
- Explain the chemistry of cell-dyes interaction
- Evaluate the effects of tissue processing on histochemistry
- Evaluate the need for quality control for histochemical techniques

3. Historical perspectives

4. Heros in histochemistry
F. V. Raspail (1794-1878)
accredited as the father of histochemistry
used iodine solution to stain starch in
vegetable tissues
used aldehyde method
for protein determination
t
s
.s W W.

5. Heroes cont’d
Others include
Vogel (1845): Iron determination
Perls (1867): Prussian method for Fe
Millon (1844): Tyrosine determination

6. Histochemistry
Study of tissue component (cells & ECM) by applying physical
and chemical conditions to microscopical preparations
without damages to tissues.
Types of tissues
1. Epithelial
2. Connective
3. Muscles
4. Nerve

7. Overview of tissue biology
Nucleolus
Nucleus
Chromatin
Cell
Organelles
Cytoplasm
Non-organelle
collagen, reticular, elastic fibril
ECM
Salts and water

8. Breaking it down
A. Simple: tissue
B. Simpler: cells
C. Simplest: protein (the most abundant), carbohydrate,
lipids, nucleic acids, pigments, etc

9. charged cationic dye such as methylene blue.
R***-HC|***-COOH****** +***ªH***+ ***R-C***H|| -
C***OO***— ***-∫H***+ ***R-C***H||-C***OO***—
|_e.(F=_iAg._ci_ 1.d_ dye_ _ _;Sc__hema____tic
r___ep_re__sen__tat__io_Ce.(n =_aB_to_f dy___e-_pro____tein

10. Cell-dyes interactions
A. Basophilia v acidophilic/ eosinophilia
B. Basic v acid dyes
1. Synthetic v natural dyes
C. Metachromasia
D. Romanowsky dyes
A. staining due its Physical properties

11. - Vital and supra vital stains
- lipid stains
B. Schiff reactions: Feulgen & PAS
C. Metals
- Silver impregnation
- Osmic acid
- Gold chloride

12. Conditions
Physical
- Forms and charges of macromolecules are exploited in
staining, e.g. Van Gieson
Chemical
- Modifying chemical groups of tissues, e.g. conversion of
hydroxyl groups in sugars to aldehyde during schiff
interaction in PAS

13. Effects of Tissue Processing on
histochemistry
1. FIXATION & DECALCIFICATION
A. Prolonged formalin fixation of liver tissue leads to polarisation of glycogen
B. Prolonged Bouins fixation or decalcification leads to destruction of nucleic
acids
C. Glyoxal-containing fixatives suppress arginine rich proteins by anionic
dyes
D. Glutaraldehyde gives false positive for Periodic acid schiff reaction

14. Effects of Tissue Processing on histochemistry
 Tissue processing: +/- of chemicals or substances
 Microtomy: folds and tissue shuttering can remove a portion of tissue
Guidelines of histochemical staining
identify which tissue component to stain
determine the appropriate fixative and tissue processing
decide the staining a specific staining procedure to use