Practical 1 Microtechniques 2024 PDF

Cells: are the structural and functional units in the body Tissues: collection of cells that perform a similar function. Tissues Epithelial Connective Muscular Nervous Organ: are composed of the four basic tissues in various proportion to perform special function. Cytology It the science deals with...

Cells: are the structural and functional units in the body Tissues: collection of cells that perform a similar function. Tissues Epithelial Connective Muscular Nervous Organ: are composed of the four basic tissues in various proportion to perform special function. Cytology It the science deals with study of cells. Microtechniques The methods by which histological sections are prepared. Histological section is a very thin slice of tissue put flat on a glass slide, mounted and covered. 1.Obtaining the tissue: the piece of tissue should be very small and fresh, taken immediately after death. 2. Fixation: Definition: Treatment of tissues by putting them in a fixative or preserving fluids. Paraffin Sections 1. Obtaining the tissue: 2. Fixation: 10 % Formalin for 24 hours 3. Washing: by running tap water to remove the fixative 4. Dehydration: Definition: removal of water Aim: Removal of water (which is immiscible with paraffin) and its replaced with alcohol (which is miscible with paraffin solvents). 5- Clearing: Replace alcohol with paraffin solvent e.g. xylol 6. Impregnation: Technique: in melted soft paraffin wax Aim: By impregnation, the wax infiltrate the tissue and replaces xylol. 6. Impregnation: 6) Embedding: in hard paraffin to make blocks. 7. Sectioning: the block is cut into thin sections with the rotatory microtome. 8. Mounting: sections on slides after floating on warm water bath. Paraffin Sections 1. Cutting the tissue 2. Fixation 3. Dehydration 4. Clearing 5. Impregnation 6. Embedding 7. Sectioning 8. Mounting Stains Def: They are colored material used for easy differentiation of tissue or cell components. Staining may be due to a chemical reaction of the dye with the cellular components. The most commonly used stains Hematoxylin and eosin (H&E); (ordinary or general stain). Any stains except H & E are called special stains. Origin Animal Carmine Plant Haematoxylin Synthetic Eosin Mode of action Chemical Hx&E Physical Sudan III Staining radicals Acidic stain Eosin Neutral stain Leishman Basic stain Hx Acidic structures e.g. nucleus, ribosomes, RER Basic structures e. g. mitochondria, SER Basic dye (Hematoxylin) Purplish Blue (Basophillic) Acidic dye (Eosin) Red or pink (Acidophillic or eosinophilic) (Hematoxylin and eosin; H&E) Stainability of cell and tissue components: - Acidophilic stained with acidic stain. - Basophilic stained with basic stain - Amphoteric stained with acidic + basic stain. Ocular Ocularlens lens (Eye (Eyepieces) pieces) Stage Objective lens C Condenser Light Source Scanning Electron Microscope L/ M E/M Up to 1000 - Magnification (eye piece power X objective power) up to 400,000 - Beam used Electron beam Light from sun beam lamp or LM TEM SEM