Light & Electron Microscopy PDF - Cell Biology Section 1

Cell Biology Microscope Section 1 Presented by : T.A Ahmed Selim Shahda Faculty of Pharmacy, Egyptian Russian University  Microscopy Microscopes have long been essential tools of cell biologists. This tutorial provides a brief overvi...

Cell Biology Microscope Section 1 Presented by : T.A Ahmed Selim Shahda Faculty of Pharmacy, Egyptian Russian University  Microscopy Microscopes have long been essential tools of cell biologists. This tutorial provides a brief overview of types of microscopes commonly used in biological studies. The two broad categories of microscopy are: Light Microscopy (LM) and Electron Microscopy (EM)  Types of Microscopes Light microscopy: Electron microscopy: uses sunlight or artificial light source uses electrons Bright field microscope Transmission electron Dark field microscope microscope (TEM) Epi-fluorescence Microscopy Scanning electron microscope (SEM)  Light Microscopy Principle: light passes through the specimen and then through a series of magnifying lenses. Light microscope is the simplest type of microscopes. Microscopes are of a great importance in studying microorganisms and biomolecules.  Bright Field Microscopes (BFM) The most common general use microscopes Bright field microscopes are named because the microscopic “field” is bright, while the object being viewed is dark. Bright field microscope characters: Simple design Light directed at specimen is absorbed to form image Unstained specimens have poor contrast Stained specimens show excellent contrast Ideal for stained bacteria, cells and tissues High resolution  Dark Field Microscopes (DFM) The dark field microscope creates a dark background to allow viewing of small unstained objects, such as motile bacteria, that would be difficult to view in a bright field. The central portion of the light is blocked, so that only diagonal light strikes the specimen and forms the image. Bright specimen, dark background Dark Field Microscopes (DFM)  Fluorescence Microscope Allows the detection of molecules and ions within cells. Fluorescent dyes absorb short wavelengths of light and emit longer wavelengths. Barrier filters and a prism select the excitation wavelength that strikes the specimen and then exclude the excitation wavelength from the detector, allowing only emitted light to reach the detector (oculars). Uses UV light source, high resolution image Special fluorescent dyes used to locate “molecules” in a specimen black background, bright-stained specimen Fluorescence Microscope  Designs of light microscope Compound microscope Inverted microscope Stereo microscope Digital microscope  Compound Light Microscope Commonly binocular (two eyepieces) Typically, the eyepiece itself allows for 10X or 15X magnification and when combined with the three or four objective lenses, which can be rotated into the field of view, produce higher generally. magnification to a maximum of around 1000X  Inverted Microscopes The basic design of bright field microscopes has been modified for special uses. Inverted microscopes allow viewing of cells in flasks, welled-plates, or other deep containersthat do not fit between the objectives and stage of standard BF microscopes.  The Stereo Microscope Stereo microscopehas two optical paths at slightly different angles allowing the image to be viewed three- dimensionally under the lenses. Stereo microscopes magnify at low power, typically between 10X and 200X  The Digital Microscope The digital microscope uses the power of the computer to view objects not visible to the naked eye. The computer software allows the monitor to display the magnified specimen. Moving images can be recorded or single images captured in the computer’s memory.  Electron microscopy - Transmission electron microscope (TEM) - Scanning electron microscope (SEM  Electron microscopy Electron Microscope(EM) is a powerful microscope available and used today, allowing researchers to view a specimen at nanometer size. The electron microscope is a type of microscope that uses electrons to create an image of the target. Electron Microscopes has practical applications in such fields as biology, chemistry, gemology, metallurgy and industry. It is used in biomedical research to investigate the detailed structure of tissues, cells, organelles and macromolecular complexes. There are two common types of EM, transmission electron microscope (TEM) and scanning electron microscope (SEM) Electron microscopy Thank you