Histo Techniques 2

Question 1

What is microtomy?

Answer 1

A method to describe the preparation or cutting of a thin section of tissue

Question 3

What is a microtome?

Answer 3

A mechanical instrument used to cut biological specimens into thin sections for microscopic examination

Question 4

What thickness is the tissue cut in the microtome?

Answer 4

2-25 micrometers

Question 5

What happens in a Rocking Microtome and what is this machine used for?

Answer 5

The block of embedded tissue is fixed to the end of a lever which moves in an arc against a fixed knife.
Used for sectioning small paraffin embedded blocks

Question 6

What is an ultra microtome?

Answer 6

A precision instrument used to section resin-embedded blocks for electron microscopy.
5-100nm sections are obtained using glass or diamound knives

Question 7

What should the water bath be filled with and heated to?

Answer 7

Deionised water and heated to between 45 - 50 degrees C

Question 8

How and why should the water baths be cleaned?

Answer 8

Should be cleaned betwen blocks during cutting by dragging a paper tissue through the water, across the surface to remove debris.
This is essential to prevent carryover between slides

Question 9

Microtomy procedure

Answer 9

All blocks are trimmed at 20um, firstly to remove excess wax and expose the full face of the block (special care with small biopsies)
After trimming, blocks should be placed on a cold plate and allowed to cool before cutting at 3um

Question 10

What to do if there is difficulty in establishing a ribbon to put in the water bath

Answer 10

Blow gently down onto the block as the section is being cut or return it to the cold plate for cooling

Question 11

What to do if a fold occurs in the specimen when in the water bath?

Answer 11

Gently tease out using a paint brush or stainless steel seeker

Question 12

What is Calbonex/ Rapid Decalcifier used for?

Answer 12

To soften bone marrow

Question 13

What is 10% Formic Acid used for?

Answer 13

To decalcify bone marrow

Question 14

What is 10% KOH used for?

Answer 14

To soften samples containing nail/ nail beds

Question 15

What does crunchy/brittle tissue mean and what should you do about it?

Answer 15

Could indicate tissue is over processed.
Ensure section of blade being used is new and block is very cold when colding
Tissue may benefit from water on the surface or softening agent

Question 16

What to do if calcium or hard deposits found on tissue?

Answer 16

Surface decalcification required
Soak in appropriate decalcifying agent

Question 17

What to does it mean if outer part of tissue will cut but the inner part will not?

Answer 17

Indicates tissue is under processed/ incomplete wax infiltration