Histology: Microscopy

human anatomy

study of the structure of the human body

macroscopic and microscopic

two subdivisions of human anatomy is ..... and .....

gross anatomy

macroscopic anatomy is called....

histology

microscopic anatomy is called....

Microscope

optical instruments consisting ofa combination of lenses, which provide an enlarged image of small objects

magnification and resolution

usefulness of any type of microscope depends on its ....and.....

magnification

ability to enlarge the image of the object being viewed

Resolution

ability to allow the observer to distinguish between two small objects situated close together

resolving power

resolution is also called...

greater

shorter the wavelength.....the resolution

optical and electron

two types of microscopes

visble light

optical microscope use ....

ultraviolet light

fluorescence microscope use ....

high velocity electrons

electron microscope use ....

bright-field microscope

most commonly used microscope is....

stereomicroscope, polarising microscope, phase contrast microscope and confocal microscope

examples of optical microscopes are ....

light source, condenser lens, stage, objective lens, ocular lens

five components of a bright field microscope

light source

produces a beam of light

condenser lens

focuses the light on the specimen

objective lens

gathers the light which has passed through the tissue specimen

objective lens

magnifies and projects the illuminated image of the specimen toward the ocular lens

numerical aperture

the ability to gather light and resolve the specimen detail depends on the...of the objective lens

4

how many objective lens are in a microscope?

4,10,40

the first 3 lens magnification

100

4th objective lens magnification

oil immersion objective

the fourth objective lens is called...

oil immersion technique

used to enhance the resolving power of the light microscope

ocular lens

further magnifies the image 10 times and focuses the resulting image on the retina of the viewer's eye

0.2 micrometer

resolving power of the bright field microscope is ....

1000 to 1500 times

a bright field microscope can magnify the images ...to ...times

histological sections

thin slices in histology.....

fixation, embedding, sectioning, staining

the four main steps in the process of preparation of the tissue for bright field microscopy

fixation

preservation of the tissue structure with the least possible alteration

fixatives

chemical compounds which render the structural components of the cells insoluble

bring about stablization of proteins by causing the formation of cross links between the protein molecules

major action of the fixatives

formalin

most common fixative

37% solution of formaldehyde gas in water

pure formalin is ...

10% formalin

general purpose formalin

paraffin

most common embedding agent

solid

paraffin is ... at room temp

microtome

sectioning of the tissue block into thin slices is carried out by the .....

3-10 micrometer thick

sections of a specimen are ....thick

basic dye

hematoxylin

basic dye

toluidine blue

basic dye

methylene blue

acidic dye

eosin

acidic dye

acid fuchsin

acidic dye

orange G

acidic dye

picric acid

hematoxylin and eosin

stains used in routine histology

polarising microscope

contains 2 polarising filters

birefringence

the capacity to rotate the direction of the vibration of polarized light

double refraction

birefringence is also known as ..,

anisotropic

substances with double retraction

isotropic

substances with single refraction

phase contrast microscope

used for the study of unstained fresh tissues or living cells

polarizer

first filter in a polarising microscope placed below the condenser lens

analyser

second filter in the polarising microscope placed between the objective and ocular lens

dark field microscope

used to study unstained and transparent specimens

out of focus light

confocal microscope are designed to eliminate the ..

1/2000

the wavelength of the electron beam is... of the visible light beam

ultrastructure

structure visible only under EM is known as ...

less than 1mm^2

specimen area of EM is..

transmission and scanning

two types of electron microscopes

transmission electron microscope

beam of electrons are deflected by electromagnetic fields

vacuum

the illuminator source of a TEM is a beam of high velocity electrons accelerated in a ...

fluorescent screen or photographic plate

the beam in TEM is focused on ....or...

2nm

resolution of a TEM

120,000 times

ultrathin tissue sections can be magnified up to .... times

scanning electron microscope

used to view the surface of a solid specimen

glutaraldehyde and osmium tetroxide

fixatives used in electron microscopy

epoxy resins

After fixation in SEM tissue is embedded in ....

40 to 100 nm thick

ultramicrotomes produce ..... thick sections

ultramicrotome

machine used to cut sections for a SEM

Transmission electron microscope

Beam of electrons can be deflected by electromagnetic fields in a manner similar to deflection of light in glass lenses

Gold or palladium

In sem the specimen is coated by…

Scanning electron microscope

Electrons do not pass through the specimen under examination