lesson 5. llight microscopy bbright-field microscopy pphase contrast microscopy ddifferential...
TRANSCRIPT
ELECTRON MI-CROSCOPY
LESSON 5
TYPES OF MICROSCOPY
Light Microscopy Bright-field microscopy Phase Contrast microscopy Differential Interference Contrast (or Nomarski) Dark-field microscopy Fluorescence microscopy Confocal Scanning microscopy
Electron Microscopy Transmission electron microscope (TEM) Scanning electron microscope (SEM)
Learning Resources
1. Junqueira’s Basic Histology ; pp 7 & 9
2. Looking at the Structure of Cells in the Microscope
http://www.ncbi.nlm.nih.gov/books/NBK26880/#A1749▪ The Electron Microscope Resolves the Fine
Structure of the Cell.▪ Images of Surfaces Can Be Obtained by Scanning
Electron Microscopy▪ Metal Shadowing Allows Surface Features to Be
Examined at High Resolution by Transmission Electron Microscopy
▪ Freeze-Fracture and Freeze-Etch Electron Mi-croscopy Provide Views of Surfaces Inside the Cell
Resolution, resolution!!!
Electron Microscopy
Why electron beams? The wavelength, much shorter than of light
Types Transmission electron microscope (TEM) Scanning electron microscope (SEM) - sur-
face contoursTEM SEM
R = 0.61λ/ N.A.
Electromagnetic lenses
• a coil of wire through which current flows• magnetic field in the center.• electrons traveling in their path down the central
hole.
TEM
Dark (Electron dense)
(Electron transparent)
Bright (Electron lucent)
Contrast in TEM
• Bright (Electron lucent) - electrons readily passed
• Dark (Electron dense) - electrons absorbed
Transmission electron microscope (TEM)
SEM TEMDIC
SEM
Scanning electron microscope (SEM)
Metal Shadow-ing
• high resolution three-dimen-sional replica of the specimen
• heavy metal shadowing of bacteria to demonstrate flagella
Freezing Techniques
•Freeze-Fracture •Freeze-Etch
TEM Section and Freeze Fracture