MICROSCOPY

Question 1

Small pieces of tissue are placed in solutions of chemicals that cross-link proteins and inactivate degradative enzymes, which preserve cell and tissue structure.

Answer 1

FIXATION

Question 2

The tissue is transferred through a series of increasingly concentrated alcohol solutions, ending in 100%, which removes all water

Answer 2

DEHYDRATION

Question 3

Alcohol is removed in organic solvents in which both alcohol and paraffin are miscible.

Answer 3

CLEARING

Question 4

The paraffin-infiltrated tissue is placed in a small mold with melted paraffin and allowed to harden.

Answer 4

EMBEDDING

Question 5

The tissue is then placed in melted paraffin until it becomes completely infiltrated with this substance.

Answer 5

INFILTRATION

Question 6

The resulting paraffin block is trimmed to expose the tissue for sectioning (slicing) on a microtome.

Answer 6

TRIMMING

Question 7

The hardened block with tissue and surrounding embed- ding medium is trimmed and placed for sectioning in an instrument called a

Answer 7

MICROTOME

Question 8

TYPES OF LIGHT MICROSCOPY

Answer 8

Bright-field, Phase-contrast, Differential interference contrast microscopy, Dark-field, Fluorescence, Confocal

Question 9

What is the most commonly used staining method?

Answer 9

Combination of the stains H&E which act as basic and acidic dyes

Question 10

Cell substances with a net negative (anionic) charge, such as DNA and RNA, react strongly with hematoxylin and basic stains; such material is said to be..

Answer 10

BASOPHILIC

Question 11

Cationic substances, such as collagen and many cytoplasmic proTeins react with eosin and other acidic stains and are said to be..

Answer 11

ACIDOPHILIC

Question 12

This microscope is most commonly used by both students and pathologists, uses o ordinary light and the colors are imparted by tissue staining.

Answer 12

BRIGHT-FIELD MICROSCOPY

Question 13

This microscope uses UV light, under which only fluo- rescent molecules are visible, allowing localization of fluorescent probes which can be much more specific than routine stains.

Answer 13

Fluorescence microscope

Question 14

This microscope uses the differences in refractive index of various natural cell and tissue components to produce an image without staining, allowing observation of living cells.

Answer 14

Phase-contrast microscope

Question 15

This microscope involves scanning the specimen at succes- sive focal planes with a focused light beam, often from a laser, and produces a 3D reconstruction from the images.

Answer 15

Confocal Microscopy

Question 16

This process localizes cell components synthesized using radioactive precursors by detecting silver grains produced by weakly emitted radia- tion in a photographic emulsion coating the tissue section or cells.

Answer 16

Autodiography

Question 17

This technique use specific enzymatic activities in lightly fixed or unfixed tissue sections to produce visible products in the specific enzyme locations.

Answer 17

Enzyme Histochemistry or Histochemical techniques

Question 18

Specific place where light rays are focused

Answer 18

Focus point

Question 19

distance between center of lens and focal point

Answer 19

Focal length

Question 20

(T/F) Short focal length = more magnification

Answer 20

TRUE

Question 21

(T/F) Shorter wavelength = greater resolution

Answer 21

TRUE

Question 22

Distance between the front surface of lens and surface of cover glass or specimen when it is in sharp focus

Answer 22

Working Distance

Question 23

• Image is formed by light reflected or refracted by the specimen
• Produces a bright image of the object against a dark background
• Used to observe living, unstained preparations
• Used to observe internal structures in eukaryotic microorganisms
• Very thin histological sections can be used if unstained or only certain components are stained, as in silver stains

Answer 23

Dark field microscope

Question 24

● Exposes specimen to ultraviolet, violet, or blue light
● Specimens usually stained with fluorochromes
● Shows a bright image of the object resulting from the fluorescent light emitted by the specimen
● Has applications in medical microbiology and microbial ecology studies
● For viewing

Answer 24

The fluoresence microscope

Question 25

● This creates sharp, composite 3D image of specimens by using a laser beam, aperture to eliminate stray light, and
computer interface
● Numerous applications including the study of biofilms
● Laser
● For demonstrating specimens

Answer 25

Confocal Microscope

Question 26

● use 20,000 - 120,000 volts of beams of electrons to create highly magnified images
● Electrons replace light as the ‘illuminating’ beam that will pass through glass lens
● Wavelength of electron beam is much shorter than light, resulting in much higher resolution and magnification
● Allows for study of microbial morphology in great detail

Answer 26

Electron Microscope

Question 27

2 types of electron microscope

Answer 27

TEM & SEM

Question 28

● Electrons scatter when they pass through thin sections of a specimen
● Transmitted electrons are under vacuum which reduces scatter and are used to produce clear image
● Denser regions in specimen scatter more electrons and appear darker
● Produces a 2D image

Answer 28

TRANSMISSION ELECTRON MICROSCOPE

Question 29

○ A type of staining that make internal and external structures of cell more visible by increasing contrast with background

Answer 29

DYES

Question 30

(T/F) ○ Basic dyes have positive charges
○ Acid dyes have negative charges

Answer 30

TRUE