Microscopy
Maurice Wetherall
University Senior College
Microscopy
“This material has been developed as a part of
the Australian School Innovation in Science,
Technology and Mathematics Project funded by
the Australian Government Department of
Education, Science and Training as a part of the
Boosting Innovation in Science, Technology and
Mathematics Teaching (BISTMT) Programme.”
Microscopes
• Our knowledge and
understanding of the structure
of cells has only been possible
as a result of the use of
microscopes.
• Light microscopes were first
used in the 16th century.
• The electron microscope
was developed in the 1930’s.
Anton Van Leeuwenhoek’s
Simple Microscope - 1670
An English Tripod Microscope
from around 1680
A 19th
Century
Microscope
A Current
Compound
(Light)
Microscope
Image From Light Microscope:
Onion Root Cells X1000
Compound Light Microscope
• Light from a light source is directed
through the specimen.
• A combination of lenses is used to
increase the resolving power of the
human eye up to 500 times.
• Resolving power (or resolution) refers
to the ability to distinguish fine detail.
Compound Light Microscope
• The magnifying power is calculated by
multiplying the individual powers of the eyepiece (ocular) and objective lenses.
• e.g. 10x eye-piece, 40x objective = 400x
• Field diameter is the actual distance across the
field of view.
• As magnifying power increases the field
diameter decreases proportionally.
Compound Light Microscope
• The amount of light passing through the
specimen can be adjusted using the iris
diaphragm. This changes the contrast.
• The condenser lens is used to
concentrate light on the specimen.
Amoeba X1000
• The following is a short movie of a living
amoeba magnified 1000X through a
compound light microscope
• An amoeba is a microscopic unicellular
animal that lives in water
• Note the cytoplasmic movement, and
also the way the whole cell moves.
Amoeba X1000
Phase Contrast Microscope
• This is a special type of light microscope, which
provides greater contrast.
• Structures, which could not usually be seen
without staining, show up.
• Staining cells kills the cells.
• Phase contrast microscopes can be used to
observe living cells.
• e.g. movement of chromosomes during mitosis
can be viewed.
Transmission Electron
Microscope (TEM)
• In an electron microscope, beams of electrons
are focussed using magnetic lenses.
• The resolving power produced is up to
500,000 times greater than the human eye.
• Because a vacuum is needed, tissue has to be
specially prepared, and so living cells cannot
be examined.
Transmission Electron
Microscope (TEM)
Mitochondria
• The following slide shows mitochondria
viewed through a transmission EM
• The internal structures of the mitochondria
are visible. They are not visible through
Light Microscopes.
Rough Endoplasmic Reticulum
• The following slide shows a section of
rough endoplasmic reticulum.
• These flattened membranes are involved
in synthesis and transport of proteins in
cells.
• The small, dark dots are ribosomes.
Smooth Endoplasmic Reticulum
Electron Micrograph of Golgi
Body
Scanning Electron Microscope
• An electron beam scans the surface of the
specimen,
• Electrons are reflected off, and collected by a
special electron detector.
• This provides an image, which appears on a
computer screen and gives an impression of the
outer shape of the specimen.
Scanning Electron Microscope at
Adelaide Microscopy
• The following slide shows Year 11 students
using one of the scanning EMs at Adelaide
Microscopy.
Human Hair in a
Scanning Electron Microscope
• The following specimens show human hair,
the first one is hair in good condition and is
from a person using shampoo and
conditioner that are free of Sodium Laurel
Sulfate and Propylene Glycol
• The second is of poor quality hair from a
person using shampoo and conditioner
containing Sodium Laurel Sulfate and
Propylene Glycol
The End