PRELIM: CH11 IMPREGNATION AND EMBEDDING (4)

15 minutes

During the initial vacuum step, the tissue remains under negative pressure for approximately:

25–75%

Vacuum impregnation can reduce normal processing time by approximately:

It reduces exposure to excessive heat.

Why does vacuum embedding reduce tissue brittleness?

Benzene and xylene

Which clearing agents are relatively easy to remove during wax impregnation?

Chloroform and cedarwood oil

Which clearing agents are more difficult to remove and may require more frequent wax changes?

4 hours

According to the notes, tissue should generally not remain in the paraffin oven for more than:

Tissue shrinkage and hardening

Infiltration with paraffin above approximately 60°C may cause:

Lymphoid tissues

Overheated paraffin can completely destroy particularly sensitive:

About 2–5°C above the melting point

To avoid excessive tissue heating, the paraffin oven should generally be maintained:

To remove dust and foreign matter

Why should fresh paraffin wax be filtered before use?

Impair impregnation and prevent formation of a good tissue block

If reused paraffin contains excessive water, it may:

100–105°C

Excess water in reused paraffin can be removed by heating it to approximately:

Twice

According to the notes, paraffin wax should be reused only:

Relatively hard wax with a higher melting point

For fixed-knife microtomes, the recommended paraffin is generally:

Harder paraffin wax

A heavier microtome knife generally requires:

Highly purified paraffin and synthetic plastic polymers

Paraplast is composed primarily of:

56–57°C

The typical melting point of Paraplast is approximately:

More elastic and resilient

Compared with ordinary paraffin wax, Paraplast is:

Provides uniform blocks and good ribboning

A major advantage of Paraplast is that it:

Its properties allow serial sections to be cut without cooling the block.

Why might cooling of the tissue block be unnecessary when cutting serial sections in Paraplast?

"Cook" the tissue and damage histologic details

During summer, using Paraplast with a very high melting point should generally be avoided because it may:

A synthetic wax substitute similar to Paraplast

Embeddol is best described as:

Bio/aid

Which paraffin substitute is specifically recommended for embedding eyes?

Paraffin containing rubber

Tissue Mat is described as:

46–48°C

Ester Wax has a relatively low melting point of approximately: