Histological Techniques

Question 1

Hematoxylin

Answer 1

• Used in LM
• Blue Dye
• Positively Charged and stains Negatively charges structures (DNA) called basophilic

Question 2

Eosin

Answer 2

Used in LM

• Pink/Orange Dye
• Negatively charged and stains positively charged substances (hemoglobin) called eosinophilic

Question 3

Periodic Acid Schiff (PAS)

Answer 3

• for carbohydrates such as glycogen
  1. Carbohydrates are oxidized with periodic acid to form aldehyde groups
  2. Schiff reagent reacts with aldehyde group to form red reaction product

Question 4

Aldehyde Fuchsin

Answer 4

A mixture of aldehyde and basic fuchsin that forms a Schiff base and stains ELASTIC FIBERS and B CELLS

Question 5

Orcein

Answer 5

Obtained from Lichens- stains elastic/collagen fibers dark brown.

Question 6

Silver Stain

Answer 6

Tissue is first oxidized, then exposed to a solution of silver nitrate thats reduced to metallic silver. Stains RETICULAR RIBERS AND GOLGI black.

Question 7

Resolution

Answer 7

The minimum distance between 2 closely opposed structures which can be distinguished as seperate

Question 8

R=???

Answer 8

R=(wavelength of source x .61)/ (numerical aperature)

*find the numerical aperature engraved on the objective lens- higher the number the better

Question 9

Types of Light Microscopy

Answer 9

• Brightfield: most common, light shines through specimen
• Flourescence: UV light excites specimen
• Phase Contrast: Good for living, unstained specimens (growing cells)

Question 10

Types of EM

Answer 10

1. Viewing ultra thin sections of samples
2. high voltage electron microscopes for thicker samples
3. Viewing metal replicas of freeze-fractures samples

Question 11

Glutaraldehyde

Answer 11

Used in EM

-fixes proteins and nucleic acids

Question 12

Osmium Tetroxide

Answer 12

Used in EM

-Fixes Lipids