Lab quiz wrap-up

Which of the following are considered buffering agents and used in buffered formalin

• Oxalic acid and sodium oxalate
• Formic acid and potassium citrate
• Disodium hydrogen phosphate and sodium dihydrogen phosphate
• Sodium monobasic phosphate and sodium citrate

What is a characteristic of a good fixative?

• Makes tissues more permeable to subsequent reagents.
• Preserves tissue in a manner that is not life-like
• Enhances putrefaction
•   Does not harden tissues quickly  

Where does chemical fixation begin?

• Center and procedures outward
• Center and proceeds inward
• Periphery and proceeds outward
• Periphery and proceeds inward

What is temperature of the tissue processor and embedding center set at to ensure that paraffin wax remains molten?

• 54-58 degrees C
• 2 to 4 degrees C above the melting point of the wax
• 2 to 4 degrees C below the melting point of the wax
• 62 degrees C

What are the glands that are most associated with hair follicles?   

• Eccrine sweat glands
• Apocrine sweat glands
• Sebaceous glands
• Sebum glands

Formalin pigment is generally formed in tissues fixed in formalin when the pH:

• Rises above 6
• Falls below 6
• Is neutral
• 7.2

Why is glacial acetic acid useful in compound fixatives?

• It precipitates the cytoplasm
• It slows the hardening process. 
• it counteracts the shrinkage effects of other reagents
•  it raises the pH of the solution

Improper preservation of tissue can be caused by:

• a delay in fixation
• rapid penetration of the fixing fluid
• prolonged storage in 70% ethanol following fixation
• an 8 hour tissue processing schedule

Why is dehydration necessary when processing tissue?

• clearing agents do not remove water
• paraffin does not infiltrate aqueous tissue
• the water in the tissue must be removed
• the clearing agent must be removed prior to wax infiltration

Why is dehydration necessary when processing tissue?

• clearing agents do not remove water
• paraffin does not infiltrate aqueous tissue
• the water in the tissue must be removed
• the clearing agent must be removed prior to wax infiltration