Microscopy

1. Light Microscope

1.1. Bright-Field Microscope

1.1.1. produces dark image against a bright background

1.1.2. requires staining

1.2. Dark-Field Microscope

1.2.1. image is formed by light reflected or refracted by specimen

1.2.2. produces a bright image against a dark background

1.2.3. used to observe living, unstained preparations

1.3. Phase-Contrast Microscope

1.3.1. converts differences in refractive index/ cell density into detected variations in light intensity

1.3.2. excellent way to observe living cells

1.3.3. stain is not necessary, view internal structures of living organisms

1.4. Fluorescence Microscope

1.4.1. exposes specimen to ultraviolet, violet & blue light

1.4.2. specimens usually stained with fluorochromes

1.5. Confocal Microscope

1.5.1. CLSM creates sharp, composite 3D image of specimens by using laser beam, aperture to eliminate stray light and computer interface

1.5.2. Numerous application inc. study of biofilms

2. Electron Microscope

2.1. employs a beam of electron in place of light wave to produce the magnified image

2.2. Scanning Electron Microscope (SEM)

2.2.1. to study the surface features of cells and viruses

2.3. Transmission Electron Microscope (TEM)

2.3.1. to examine viruses or the internal ultrastructure in thin sections of cell

2.4. Electron Crytomography

2.4.1. rapid freezing technique provides way to preserve native state of structures examined in vacuum

2.4.2. images are recorded from many different structures to create 3-D structures

2.4.3. provides extremely high resolution images