Introduction: - Micro-techniques for tissue preparation. - Stains. ... Paraffin block are cut by microtome using metal knife, into thin sections ~ 6µ. - Capsules are cut ...
Histology - Cytology: Cell, Nucleus, DNA, and Chromosomes. - Tissues: 4 basic tissues including; Epithelium, Connective (Cartilage, Bone, Blood), Muscular, and Nervous tissues. - Systems and different Organs.
Introduction: - Micro-techniques for tissue preparation. - Stains. - Microscopes. - Special techniques used for medical diagnosis. - Cell, Tissues and Organs.
Micro-techniques for tissue preparation - Using Light or Electron Microscope.
2- Dehydration: Gradual removal of water from the tissue using ascending grads of ethyl alcohol to prevent tissue shrinking.
3- Clearing: Replacement of alcohol in tissue by clearing fluid like xylem, benzene, or acetone
4- Embedding: - Tissues are impregnated in paraffin - Tissues are impregnated in Epon in gelatin capsule. 1
5- Cutting: - Paraffin block are cut by microtome using metal knife, into thin sections ~ 6µ. - Capsules are cut by ultra-microtome, using glass or diamond knife, into ultra thin sections 50-100nm. 6- Mounting: - Sections spread on the hot plate and mounted on glass slides. - Sections mounted on metal grids.
7- Staining: - Variable stains are used for specific tissues. - Stained by heavy metals like lead nitrate and uranyl acetate.
Stains - Special dyes used to stain the histological sections and make them ready for microscope examination. - Heamatoxylin and Eosin are most common used.
Types of stains 1- Reaction of stain: - Acidic
Eosin stain
- Basic
Heamatoxylin stain
- Neutral
Leishman stain
2- Physical stain: stain dissolve in tissue without any chemical reaction such as : SUDAN III for fatty tissues. 3- Vital stain: Staining living tissue inside the body. ---------Trypan blue stain. 4- Supra-vital stain: Staining living tissues outside the body. -----Brilliant cresyl blue. 5- Metachromatic stain: Staining the tissues with a color different from the original color of stain. ----------Toluidin blue staining for Mast cells. 6- Polychromatic stain: Staining the tissues with multiple colors in spite of using a single stain. -----------Geimsa stain for blood. 7- Orthocromatic stain: Staining the tissues with the same color of the stain, such as H&E. 8- Histo-chemical stain: Staining the different chemical components of the cell. 9- Immuno-histo-chemical stain: Localization and staining specific proteins by the antigen antibody reaction. 2
