Histology & Cytology

Question 1

What is Histology?

Answer 1

Tissues are processed to see malignancy under microscope. Can be fresh or fixed.

Question 2

Fixation

Answer 2

• Submerged in solution ASAP
• 10-20x volume of specimen
• Solution denatures protein (prevents autolysis)
• Usually neutral buffered formalin (rarely glutaraldehyde or B5)

Question 3

Grossing

Answer 3

• Description done by pathologists
• Sliced into 3-5mm pieces to go into cassettes

Question 4

Decalcifying

Answer 4

• Removes calcium from bone or scar tissue
• Must be fixed before decalcified

Question 5

Dehydration

Answer 5

Removal of water using increasing strengths of alcohol (ethanol or acetone)

Question 6

Clearing

Answer 6

• Removal of dehydration agent using xylene (could be toluene or histoclear)
• Decreases the cloudiness of a specimen (poor dehydration = milky xylene (water in xylene)

Question 7

Infiltration

Answer 7

• Removal of clearant
• Infiltration of paraffin wax (must be dewaxed before stain or stain won’t penetrate)

Question 8

Mounting

Answer 8

Permount + coverslip

Question 9

Resinous Mount

Answer 9

Permount, aqueous mount, gelatin

Question 10

STAT Processing

Answer 10

• 2-4 hours instead of 12-16
• Sections frozen by cryostat
• Cut with microtome
• Frozen, cut, stained, viewed
• Specimen is then thawed and processed as normal
• Tech SETS UP

Question 11

Stains: Hematoxylin-Eosin (H&E)

Answer 11

Hematoxylin - Blue

Eosin - Red/orange/pink (differential stain)

Question 12

Stains: Progressive

Answer 12

Specimen left in dye until it’s ready

Question 13

Stains: Regressive

Answer 13

Specimen is over stained and excess stain is removed

Question 14

Bluing

Answer 14

• Must be mildly alkaline

Question 15

What’s the most important step of Bluing?

Answer 15

Differentiation

Question 16

What is Cytology?

Answer 16

• Less traumatic sampling
• Relies on good samples
• Can be fresh or fixed
• Liquid based or cell block

Question 17

Stains: Pap

Answer 17

Fixative = Alcohol
Hematoxylin = Aqueous
Counterstain = Alcohol
Clearing = Xylene

Question 18

Stains: DiffQuick

Answer 18

Rapid Romanowsky (stain)
- Eosin-methylene blue
- 10 dips in methanol to fix
- 5 dips in eosin
- 10 dips in methylene blue/azure
- Water rinse

Question 19

Stains: Retic Stain

Answer 19

Supravital stain = saline + methylene blue/brilliant cresyl blue + 15 mins

Question 20

Too thick blood smear?

Answer 20

Too big of blood drop

Question 21

If your Hematoxylin has a sheen, it needs what?

Answer 21

To be filtered

Question 22

If your Wright’s stain is too blue, it’s what?

Answer 22

Buffer is too acidic