Types and Parts of microscopes (Light&Electron)

. Types of microscopy: 1-Light microscopy 2-Electron microscopy

-:Parts of light microscope

Ocular lens [2 Eye pieces]: Magnify the image X 10 

Objective lenses: Magnifies the image X 4, X 10, X 40 & X 100 for higher magnification of more detailed areas

The condenser: Collects and focuses a cone of light that illuminates the tissue slide on the stage

Stage control: Moving the slide

How to calculate the total magnification of light microscopy? >> Total Magnification power of light microscope = >> Magnification power ocular lens [10] X Magnification power of objective lens [4, 10, 40 & 100]

Some important measurements & Units >> Centimeter (cm) = 10 Millimeter (mm) >> Millimeter (mm) = 1000 Micrometer (µm) >> Micrometer (µm) = 1000 Nanometer (nm)

The difference between magnification power & resolution power

 Magnification power = Degree of enlargement >> The maximal magnification power of: -L.M is 1000 times & -E.M is 120,000 times 

Resolution power = The least distance between two points that can be seen as two [not one point] The maximal resolution power of: -L.M is 0.2 µm & E.M is 3 nm

Types of Electron Microscope 1- Transmission Electron Microscopy 2- Scanning Electron Microscopy

Transmission Electron Microscopy >> Based on the interaction of tissue components with beams of electrons passing through the tissue sections >> Produce an image with black, white and intermediate gray regions >> Electron-lucent = White (Bright) areas through which electrons passed >> Electron-dense = Dark areas where electrons were absorbed or deflected

Scanning Electron Microscopy >> Provides a high-resolution view of the surfaces of cells, tissues, and organs. >> The beam of electrons does not pass through the specimen >> The surface of the specimen is spray-coated with a very thin layer of heavy metal (often gold) → Reflects electrons in a beam scanning the specimen. >> The reflected electrons are captured → 3D-Black & white