The Study of Microbial Structure: Microscopy and Specimen Preparation
Microbiology usually is concerned with organisms so
small they cannot be seen distinctly with the unaided
eye. Because of the nature of this discipline, the microscope
is of crucial importance. Thus it is important to understand
how the microscope works and the way in which specimens
are prepared for examination.
The chapter begins with a detailed treatment of the standard
bright-field microscope and then describes other common types
of light microscopes. Next preparation and staining of specimens
for examination with the light microscope are discussed. This is
followed by a description of transmission and scanning electron
microscopes, both of which are used extensively in current microbiological
research. The chapter closes with a brief introduction
to two newer forms of microscopy: scanning probe microscopy
and confocal microscopy.
1.The Light Microscope
Microbiologists currently employ a variety of light microscopes in
their work; bright-field, dark-field, phase-contrast, and fluorescence
microscopes are most commonly used. Modern microscopes are all
compound microscopes. That is, the magnified image formed by the
objective lens is further enlarged by one or more additional lenses.