Introduction to Histology Lecture Notes PDF

INTRODUCTION TO HISTOLOGY Prof. Manal M. Sayed Faculty of Physical Therapy Sphinx University 2024-2025 1  INTRODUCTION TO HISTOLOGY Learning Objectives:  Define Histology.  Identify the microscope.  Recognize the types of mic...

INTRODUCTION TO HISTOLOGY Prof. Manal M. Sayed Faculty of Physical Therapy Sphinx University 2024-2025 1  INTRODUCTION TO HISTOLOGY Learning Objectives:  Define Histology.  Identify the microscope.  Recognize the types of microscopes.  Compare between light & electron microscopes.  Identify the principle of preparation of histology slides for microscopic examination. Types of staining methods. 2  What is Histology? Histology is the study of the microscopic structure of cells, tissues and organs of the body. *Tissues have two interacting components: cells and extracellular matrix (ECM). *Because of the small size of cells, the study of histology depends on the use of the microscope. 3  Microscope Definition: The microscope is an instrument having magnifying lenses for inspecting objects too small to be seen by the human eyes. Functions: 1.Resolution. 2.Magnification. 4  Resolution *Definition: Resolution is the power of the microscope to distinguish fine details. *Resolution of the microscope depends mainly on the quality of its objective lens. * Resolving power of the human eye is 0.2 mm. * Resolving power of the light microscope (LM) is 0.2 µm. * Resolving power of the electron microscope (EM) is 1 nm. 5  Magnification Magnification is of value ONLY when accompanied by resolution. Resolving power of LM (0.2µm) allows clear images magnified 1000 times. Resolving power of EM (1 nm) allows clear images magnified 100,000 times. 6  Let’s Think A B C D 7  Types of Microscopes Light microscope Electron microscope (LM) (EM) TEM SEM 8 a) Light microscope (LM): is based on the passage of light through thin stained tissue sections. b) Electron microscope (EM): is based on the use of electron beams and electromagnetic lenses. There are two main types of EM: 1. Transmission electron microscope (TEM): is based on the passage of electron beam through ultrathin tissue sections to study fine tissue structures. 2. Scanning electron microscope (SEM): The electron beam scans the surfaces of cells, tissues and organs, providing a three-dimensional (3D) image. 9 10  LM TEM SEM 11  LM TEM An epithelial tissue examined by LM SEM 12 An epithelial tissue examined by LM 13 The same epithelial tissue examined by TEM 14 The same epithelial tissue examined by SEM 15  Main Differences between LM & EM LM EM Resolving 0.2 um 1 nm Power Magnification 1000 times 100,000 times Source of Light (have longer Electron Beam Illumination wavelength) (have shorter wavelength) Lenses Glass lenses Magnetic lenses Image of tissue Colored Black and white 16 *Thin stained tissue sections must be prepared for microscopic examination of the tissue. 17  Types of Stains Histochemical and General staining Special staining cytochemical staining methods methods methods 18  Staining *Types of staining methods: 1. General staining methods: are used to reveal general structure of the tissue. The most common general stain used is the combination of hematoxylin and eosin (H&E): -Hematoxylin is a blue basic dye which stains acidic cell components such as nucleic acids (DNA & RNA). The cell components which have an affinity for basic dyes are termed basophilic. -Eosin is a pink acidic dye which stains basic cell components such as most cytoplasm proteins (e.g., mitochondria). The cell components which have an affinity for acidic 19 dyes are termed acidophilic.  The most common general stain used is the combination of Hematoxylin and Eosin (H&E) 20 2. Special staining methods: are used to reveal certain tissue components, e.g., Sudan black dye stains lipids. 3. Histochemical and cytochemical staining methods: are specific chemical staining methods based on specific binding of the dye with a particular tissue component , e.g. Periodic Acid Schiff (PAS) reaction stains carbohydrates (glycogen). 21 Sudan black dye for staining of 22 lipids PAS reaction for identification of 23 glycogen Self–exam 24 Complete: 1. The two interacting tissue components are …………… and …………………. 2. Study of histology depends on the use of ……………….. 3. The two main functions of microscopes are …….……… and ………………….. 4. Electron microscopes are based on the use of beam of …………... 5. To study tissues by the microscope, ………………………sections must be prepared. 6. …………….. cell components are stained by acidic dyes. 25 Enumerate: 1. Types of electron microscope. 2. Functions of the microscope. 3. Types of staining methods. 26 Choose the correct answer: * The electron microscope is characterized by which of the following? a. Glass lens. b. Magnetic lens. c. Colored image. d. Use of light as a source of illumination. * which microscope can provide 3D pictures? a. Transmission EM. b. Scanning EM. c. Light microscope. d. Polarized microscope. 27 * To study lipid-rich structures, we use: a. Unstained tissue. b. Periodic acid-Schiff reaction. c. Sudan black dye. d. Hematoxylin dye. * For proper light microscopic examination, we use: a. Thick tissue sections. b. Thin stained tissue sections. c. Unstained tissue sections. d. Ultrathin sections. 28  Match Column A&B Column A Column B 1- Magnification a. Power of microscope to distinguish fine details 2- Resolution b. Provide a 3-D image 3- Scanning electron c. Stains lipids microscope 4- Light microscope d. Is 100,000 times in electron microscope 5- Sudan Black dye e. Stains glycogen 6- PAS reaction f. Has glass lenses 29  Lecture References - Junqueira's Basic Histology: Text and Atlas 15th Edition. Thank you 30