General Histology PDF

GENERAL HISTOLOGY Ebtehal Zaid Hassen Saleh Assistant Professor of Histology and Cell Biology Faculty of medicine  Histology Is the science dealing with the structure of cells, tissues and organs with correlation to their function. The human body i...

GENERAL HISTOLOGY Ebtehal Zaid Hassen Saleh Assistant Professor of Histology and Cell Biology Faculty of medicine  Histology Is the science dealing with the structure of cells, tissues and organs with correlation to their function. The human body is formed of : Cells tissues organs systems  Cells - The smallest and structural units of all living organisms Cells Tissue Organ System - Cells vary in size, shape and function. - Each cell consists of nucleus and cytoplasm - The cells must be examined under microscopes because of their minute size (4- 200 micrometer). -  Tissues They are formed of similar or related cells that function in a particular manner or serve a common purpose. There are four basic tissues in our body: Epithelium Connective tissue Muscular tissue Nervous tissue  Organs ✓ The different tissues are assembled to form organs e.g. stomach, lung and liver. Each organ performs a special function. Systems ✓ They are formed of different organs collected to perform associated functions such as digestion, respiration and excretion.  Microtechnique They are methods used to prepare tissues for the microscopic examination after staining. They are three techniques: Paraffine technique: the most common one.  Histological staining Hematoxylin & eosin (H&E): The most commonly used stain in routine histology. It is formed of: Hematoxylin: basic dye that stains the acidic component with blue color (basophilic). e.g. Nucleus, ribosome. RER. Eosin: acidic dye that stains the basic component with red color (acidophilic). Cytoplasm is usually the basic. Some structures Can`t be stained with H&E (need special stains).  MICROSCOPY The importance of a microscope: its capacity to magnify small objects (magnification) and to reveal their fine details (resolution). Types: 1. Light microscopes (LM): ✓ Light microscope: use day light or electric lamb as a source of illumination. 2- Electron microscope (EM): ✓ Transmition electron microscope (TEM): Used to visualize the internal structures of the cell e.g. mitochondria, GA, RER. (very high magnif. Power) ✓ Scanning electron microscope (SEM): used to visualizes the surface ultrastructures e.g. microvilli, cilia.  TEM LM source of illumination: Beam of electron day light or electric lamb Magnification power: Up to 200,000 Limited up to1500 Images: Black and white Colored (no colored images) dark (electron dense) pale (electron lucent) Staining: Heavy metals H&E the most common