1. Interpretation of Histological sections
Lecturer Farah E. Ismaeel

2. Of histological slides Preparation

3. Fixation Small pieces of tissue are placed in solutions of chemicals
Preserve by cross-linking proteins and inactivating degradative enzymes
Physical & chemical fixation (formaldehyde 37%)

4. Dehydration
Ethanol 70%
The tissue is transferred through a series of increasingly concentrated alcohol solutions, ending in 100%, which removes all water
Ethanol 80%
Ethanol 90%
Ethanol 99%

5. Clearing
Alcohol is removed in xylene or other solvents in which both alcohol and paraffin are miscible.

6. Infiltration & embedding
The tissue is then placed in melted paraffin until it becomes completely infiltrated with this substance.
The paraffin-infiltrated tissue is placed in a small mold with melted paraffin and allowed to harden

7. Sectioning
Microtome used for sectioning paraffin-embedded tissues for light microscopy
1 and 10 μm thick sections put on glass slides

10. Staining
Using basic dyes to stain acidic components (basophilic) like nucleic acids (BLUE-VIOLET)
Using acidic dyes to stain basic components (acidiophilic) like proteins with amino groups PINK
Basic dyes that stain basophilic components: toluidine blue, methylene blue & Hematoxyline
Acidic dyes stain the acidophilic components: orang G & Eosin
Hemotoxylin & Eosin is the most used stain

11. Hematoxylin only
Eosin only
H&E

13. Thank you for listening