Light Microscope and Electron Microscope [Best one]

1- Ocularlense
receive the image from the objective lens, enlarge it and project it
to your eyes
3- Arm
vertical piece supports the head of the microscope, the stage,
the condenser, and focusing controls
2- Objective Lense
receive the image from the specimen slide and enlarges it
three or four lenses are usually located on revolving nosepiece
4- Base
horizontal piece ; supports microscope

5- Stage
platform which supports slide ; hole in center allows light from
condenser to pass through
6- Head
top part of the microscope; contains mirrors which reflect
images to the ocular lenses
7- iLLumination
located above base; includes field diaphragm and adjusting
ring used to control the width of light beam passing through

8- Condenser
series of lenses which focus light on the specimen slide; can be
moved up and down by a knob on the side
9- Diaphragm
controls width of light beam passing through the condenser to the
specimen slide
10- Knobs for moving slides
control fine movement of the slide holder; front-to-back, side-to-
side
12- FineFocus Control11- Course Focus Control
moves the stage up and down to bring image
into final focus; (blue arrow)
moves the stage up and down to bring the image
of the specimen into approximate focus; (black
arrow)

Total Magnification
Oil Immersion
Objective Lens
High PowerObjective
Lens
Low Power Objective
Lens
ScanningObjective
Lens
magnification
by 100x
magnification
by 40x
magnification
by 10x
magnification
by 4x
OcularLenses
magnification by 10x normal size
Total Magnification = Magnification of ocular lens x

TissuePreparationfor Light Microscope
To make Tissue hard and solid
2-Freezing Technique1- Paraffin Technique
For Lipids and Enzyme histochemistryRoutine and commenest method
1- Sample
Small sample = specimen of tissue .5 cm x .5 cm x .5 cm
2- Fixation
-put in fixative = formalin 10% most commonly used
-prevents putrefaction and autolysis
3- dehydration
-gradual removal of water from tissue to be miscible with paraffin
-put in ascending grades of alchol 70% , 90% , 100% gradually

4- clearance
-put tissue in xylene = xylol which makes it clear
-Xylene is miscible with paraffin and will replace alcohol which is not miscible
with paraffin
5- impregnation
-infiltration of tissues with parrafin in the oven
-put the tissue in soft paraffin then hard paraffin
6- embedding
Put the tissue in hard paraffin to obtain paraffin block
7- sectioning
By rotatory microtome (5-8um thick)

8- Staining
Stain typesClassificationDefinition
1- Acidic stain : Eosin
2- basic stain : Haematoxlin
3- neutral stain : leishman
1- natural of plant origin as
haematoxylin.
2- synthetic as eosin
Dye or substance used
for staining of sections
to differentiate
structures by different
colours

WHATISANELECTRONMICROSCOPE?
The electron microscope is a type of microscope that uses a beam
of electrons to create an image of the specimen.
It is capable of much higher magnifications and has a greater
resolving power than a light microscope, allowing it to see much
smaller objects in finer detail.
They are large, expensive pieces of equipment, generally standing
alone in a small, specially designed room and requiring trained
personnel to operate them.

HISTORYOFEM
The first electron microscope prototype was built in 1931 by German engineers Ernst
Ruska and Max Knol, capable of magnifying objects by four hundred times, it demonstrated
the principles of an electron microscope
However, two years later, Ruska constructed an electron microscope that exceeded the
resolution of an optical (light) microscope
Manfred von Ardenne pioneered the scanning electron microscope and his universal
electron microscope.
Siemens produced the first commercial TEM in 1939, but the first practical electron
microscope had been built at the University of Toronto in 1938, by Eli Franklin Burton and
students Cecil Hall, James Hillier, and Albert Prebus

Electron microscope constructed by Ernst
Ruska in 1933.

TYPESOFELECTRONMICROSCOPES
Transmission Electron Microscope (TEM)
Scanning Electron Microscope (SEM)
Reflection Electron Microscope (REM)
Scanning Transmission Electron Microscope (STEM)

TRANSMISSIONELECTRONMICROSCOPE(TEM)
The original form of electron microscopy, Transmission electron microscopy (TEM) involves
a high voltage electron beam emitted by an electron gun, usually fitted with
a tungsten filament cathode as the electron source.
The electron beam is accelerated by an anode with respect to the cathode, focused by
electrostatic and electromagnetic lenses, and transmitted through a specimen that is in part
transparent to electrons and in part scatters them out of the beam.
When it emerges from the specimen, the electron beam carries information about the
structure of the specimen that is magnified by the objective lens system of the microscope.
The spatial variation in this information (the "image") is recorded by projecting the
magnified electron image onto a fluorescent viewing screen coated with a phosphor or
scintillator material such as zinc sulfide

SCANNING ELECTRON MICROSCOPE
(SEM)
The Scanning Electron Microscope (SEM)produces images by detecting low energy
secondary electrons which are emitted from the surface of the specimen due to
excitation by the primary electron beam.
In the SEM, the electron beam is rastered across the sample, with detectors
building up an image by mapping the detected signals with beam position.
The TEM resolution is about an order of magnitude greater than the SEM
resolution, however, because the SEM image relies on surface processes rather
than transmission it is able to image bulk samples and has a much greater depth of
view, and so can produce images that are a good representation of the 3D structure
of the sample.

This is an image of an
ant using an electron
microscope (scanning
microscope )

DIFFERENCE BETWEEN
TEM & SEM
TRANSMISSION
E-MICROSCOPE
Higher resolution
Flat (2D) images
Specimen requires
thinning which is tiring
and time consuming
Expensive
Relatively detrimental
for human health
SCANNING
E-MICROSCOPE
Lower resolution
3D images
Simple to prepare
specimens
Cheap
Relatively safe to use

SCANNING TRANSMISSION
ELECTRON MICROSCOPE (STEM)
The Scanning Transmission Electron Microscope is very
powerful , and highly versatile instrument , capaple of atomic
resolution imaging and nanoscale analysis.
The high resolution of the TEM is thus possible in STEM. The
focusing action occur before the electrons hit the specimen in
the STEM, but afterward in the TEM.
The ability to scan the e beams allow the user to analyse the
Sample with different techniques such as electron energy loss
spectatory and enery dispresive X-RAY
It is also useful to understand the nature of the material in the
sample

REFLECTION ELECTRON
MICROSCOPE (REM)
Reflection Electron Microscope uses an electron beam which is
incident on a surface, but instead of using the transmission
(TEM) or secondary electrons (SEM), the reflected beam of
elastically scattered electrons is detected. This technique is
typically coupled with Reflection High Energy Electron
Diffraction and Reflection high-energy loss spectrum

Light Microscope and Electron Microscope [Best one]

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Light Microscope and Electron Microscope [Best one]