Microscopy

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Types of microscopes

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Microscopy

compound microscope

total magnification=objective lens magnificationxocular lens magnification

ocular lenses magnification(10x)

objective lenses magnification (10x,40x and 100x/oil-immension lens.)

illuminator,condenser,objective lenses,ocular lenses

uses visible light as a source of illumination

image formed by action of more than 2 lenses

resolution

the ability to distinguish two adjacent points

magnification

size of the image or point

types of light microscopes

confocal microscopy

transmission electron microscope

scanning electron microscope

fluorescence microscope

has application in medical microbiology and microbial ecology studies

shows a bright image of the object resulting from the fluorescent light emitted by the specimen

specimens usually staubed with fluorochromes

exposes specimen to UV ,violet or blue light

resolving power 100 times than light microscopes

the wavelength of electron microscope is only 0.01 Ǻ

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

phase contrast microscope

some light rays from hollow cone of light passing through unstained cell slowed/out of phase(dark against bright background)

excellent way to observe living cells

stain is not necessary,view internal structures of living organisms

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

dark-field microscope

image is formed by light reflected or refracted by specimen

used to identify bacteria such as Trepanoma pallidum,the causative agent of syphilis

used to observe internal structures in eukaryotic organism

used to observe living,unstained preparations

produce a bright image of the object against a dark background

bright-field microscope

produce dark image against a brighter background

Units of measurement

microbes and structural components->micrometers,nanometers,angstroms

metric system

preparation of specimens for light microscopy

wet mount

smears

staining

special staining

differential staining

simple staining

fixation

preparing smear

electron microscope

mycoplasma,viruses,ribosomes,proteins,lipids,small molecules,atoms

light microscope

magnification due to objective lens or ocular lens

properties of light

absorption,transmission,reflection,refraction

eukaryotic cells,nucleus,most bacteria,mitochondrion

types of stain

iodine,methylene blue,eosin Y,Toluidene blue,Wright's stain,crystal violet,aceto-orcein,Sudan III

goals of microscopy

render the details visible to the human eye or camera

separate the details in the image

produced a magnified image of the specimen

introduction to microscope and microscopy

microscope->instrument to observe microorganism

light microscope,electron microscope

cells are microscopic