Cytology, Histology

Question 1

– routine laboratory microscope used for studying tissue sections

Answer 1

Light (bright field) microscope

Question 2

– used to study cytology or internal structures of cells; study of electron micrographs

Answer 2

Transmission electron microscope (TEM)

Question 3

–used to study the surface features of cells and tissues; obtain a 3-dimensional picture of the tissue

Answer 3

Scanning electron microscope (SEM)

Question 4

– permits one to determine whether biological materials have different refractive indices along different optical axes

Answer 4

Polarizing microscope

Question 5

– used to study living tissue; works on principal of different refractive indices of cellular and sub-cellular components

Answer 5

Phase microscope

Question 6

– a modification of the phase microscope used for the study of living tissue

Answer 6

Interference microscope

Question 7

– uses UV light as the light source; used to examine the presence of fluorescent material in tissue sections

Answer 7

Fluorescence microscope

Question 8

– uses a laser energy beam; used to optically section a cell and with the appropriate computer equipment can reconstruct a 3-D image of the cell

Answer 8

Confocal scanning microscope

Question 9

a. Purpose: to preserve tissue morphology and chemical composition.
Accomplished by rendering tissue insoluble by precipitating proteins and carbohydrates (stabilizes the structure)
b. Commonly used fixatives: 10% buffered formalin, glutaraldehyde, alcohol, osmic acid

Answer 9

Fixation

Question 10

a. Purpose: to remove water from tissues so that tissue is miscible with clearing agent
b. Alcohols commonly used as dehydrating agents

Answer 10

Dehydration

Question 11

a. Purpose: to replace alcohol with an agent miscible with paraffin
b. Toluene, xylene, benzene

Answer 11

Clearing

Question 12

a. Purpose to replace clearing agent with embedding material

b. Paraffin, methacrylate, celloidin, gelatin

Answer 12

Infiltration and embedding

Question 13

a. Purpose: to produce thin sections through which light will pass. Paraffin sections cut from 5-7 μm thick
b. Done on an instrument known as a microtome

Answer 13

Sectioning

Question 14

a. Purpose: to impart color to a tissue

b. Hematoxylin and eosin (H & E)

Answer 14

Staining

Question 15

Artifact due to lysosomal digestion of the cells.

Answer 15

Post-mortem degeneration –

Question 16

Artifact due frequently to reagents used in preparing paraffin sections, resulting in empty to clear spaces which during life were occupied by tissue components.

Answer 16

Shrinkage –

Question 17

Artifact that occurs when formalin is not properly buffered.

Answer 17

Precipitates –

Question 18

Artifact due to defect in paraffin section.

Answer 18

Wrinkles and folds –

Question 19

Artifact due to defect in knife, resulting in the tearing or scraping of the tissue when the section is cut.

Answer 19

Nick in the microtome knife –

Question 20

Cause of artifacts frequently due to pinching of the tissue when removing tissue from the body.

Answer 20

Mishandling of the tissue –

Question 21

the atomic groups upon which color of a stain depends (-N=N-)

Answer 21

Chromophore –

Question 22

Stain that has chromophore associated with the basic radicle (cation; +):

Answer 22

basic stain

Question 23

structures in the cell or tissue that love basic stains; e.g. nucleus – large number of PO4(3-) radicles (acid radicles)

DNA – chromosomes; heterochromatin
RNA – nucleolus and cytoplasmic ribosomes

Answer 23

Basophilic substances –

Question 24

Blue to purple basic stain:

Answer 24

Hematoxylin

Question 25

Dye has the chromophore associated with the acid radicle (anions; -):

Answer 25

Acidic or anionic stain

Question 26

structures in the cell or tissue that love acid stains

e.g. proteins – large number of basic groups (cations; +) associated with the side chains

Answer 26

Acidophilic substances (eosinophilic substances) –

Question 27

red to pink acid stain?

Answer 27

Eosin

Question 28

a. a stain for connective tissue (collagen) rather than cells
b. e.g., Masson’s, Mallory’s

Answer 28

Trichrome stain

Question 29

a. a stain for the elastic fibers or elastic tissue in connective tissue
b. e.g., aldehyde fuchsin; orcein; resorcin-fuchsin

Answer 29

Elastic stains

Question 30

a. a stain for reticular fibers in connective tissue; also used in staining cells of the central nervous system
b. connective tissue fibers love silver (argyrophilic) and stain black

Answer 30

Silver impregnation stains

Question 31

Nucleic acids (DNA and RNA) stains:

Answer 31

Feulgen staining reaction

luekofuchsin (shiff reagent) –> aldehyde shiff (product, colored)

Question 32

Carbohydrate (e.g., glycogen) stain

Answer 32

Periodic acid-Schiff reaction (PAS)

Question 33

Fat stains:

Answer 33

a. Oil red O (stains fats red) and Sudan black (stains fats black) commonly used
b. soluble in both alcohol and fats

Question 34

Protein stains?

Answer 34

a. Specific stains for amino acids or groups of amino acids available, but no longer used
b. Immunocytochemistry is used extensively for localizing specific proteins in cells or tissues