Tuesday, November 10, 2009

Microtomy =D

Hi everybody,

Sorry for the very late posting. This would be the final post of the whole 20 weeks! Haha..I would like to talk about Microtomy as it the the last area that i'm posted to.

Subject Title: Lab Technique

Topic: Microtomy

Principle: The principle of microtomy is to sectioned tissue specimens into thin sections so that they can viewed and diagnose under microscope.

Below is a picture of the rotary microtome used for microtomy.



Materials Required

Alcohol Floatation bath 1
Soft Pencil 1
Rotary Microtome 1
Microscopic glass slides 1
Disposable microtome blade 1
Cryoplate 1
Warm floatation bath 1

Steps involved:

1) The block is required to shave first before cutting. The paraffin wax block is secured to the block holder of the microtome and adjusted it to ensure that it clears the knife. THe block holder screws are also readjusted to place the block parallel to the knife. During shaving, while the machine is manually advanced, the block is repeatedly sectioned at 20 microns thickness per slice. Shaving is stopped when the entire surface of the tissue is exposed. The block is then removed from the holder.

2) All blocks should be shaved so that dense and hard tissue can be identified more rapidly and separated from the rest. Those blocks will then pre-treated before sectioning. By doing so, it can prevent nicks and scorelines to the blade. It can also ensure that all staples or sutures are removed from the blocks before sectioning as pathologists might forget to remove them during trimming. Hard bone can also be softened first in 10% commercial fabric softener for 5 minutes, so that the tissue can be sectioned more easily.

3) After the blocks are softened, they are placed face down on the cryoplate to chill the block to allow fast sections.

4) The blocks are secured and adjusted to ensure that it is parallel and clears the knife. It is sectioned at 3-4 microns using the handwheel by allowing the block to advance automatically or manually.

5) The section is then lowered onto the floatation bath. If the tissue has difficulty in spreading, it is placed on alcohol floatation bath first to increase the surface tension before transferring onto the warm floatation bath. The section is then transferred onto a glass slide where the corresponding biopsy number is written on the frosted end of the glass slide.

6) The glass slides are separated according to their respective stains such as H&E, special stains and unstained slides.

In our lab, different biopsies are sectioned at different thickness and different number of slides are required. Below is some examples of different types of tissue biopsies and the thickness and number of slides that are required.



I will stop here for now. Please feel free to ask questions =D
Enjoy your holidays =D

Lok Pui
(0704138G)