PRELIM: CH11 IMPREGNATION AND EMBEDDING (3)

A transfer arm controlled by electrical current

What moves tissue from one processing reagent to another in the automatic processor?

Molten paraffin is viscous, so agitation improves penetration.

Why is agitation desirable during paraffin infiltration?

The paraffin wax should be changed.

During automatic processing, the presence of an odor from the clearing agent in the final wax bath suggests that:

Dehydration

Which stage is considered the most critical stage of tissue processing according to the notes?

Inadequate dehydration is difficult to correct once tissue enters paraffin.

Why should dehydration fluids be changed frequently?

The first 100% ethanol bath

After two complete processing runs of sufficiently loaded specimens, which ethanol bath should be discarded?

Once a week

The clearing agent and dilute ethanols should generally be changed at least:

To reduce the possibility of spillage and ensure proper processing

Why should fluid and wax containers in an automatic processor be filled to the appropriate level?

Removed, with spills wiped away

Wax accumulating on surfaces of the processor should be:

3°C above the melting point of the wax

Wax bath thermostats should generally be set at least:

Hold on the first ethanol bath until the next morning

If an automatic processor is operated overnight, specimens should preferably be programmed to:

It may become hard and brittle.

Why should tissue not remain in hot paraffin longer than indicated?

Negative atmospheric pressure

Vacuum embedding involves wax impregnation under:

Reduces the time tissues are exposed to high temperatures

One major benefit of vacuum embedding is that it:

Air bubbles and residual clearing agent

Vacuum embedding helps remove:

Urgent biopsies and delicate tissues such as lung, brain, and eyes

Vacuum embedding is particularly useful for:

• Lung

• Brain

• Eye

Which of the following are specifically listed as a tissue for which vacuum embedding is particularly recommended?

Wax baths, a fluid trap, and a vacuum gauge

A vacuum infiltrator or embedding oven may contain:

760 mm Hg

A vacuum of up to approximately what level may be applied using a water or mechanical pump?

500 mm Hg

According to the specific vacuum embedding oven description, the degree of vacuum should NOT exceed:

2–4°C above the wax melting point

The water-jacket surrounding the vacuum chamber is generally maintained:

To prevent water from being sucked back into the trap and vacuum chamber

What is the function of the stopcock in the vacuum embedding system?

Slowly and gradually

During vacuum embedding, air should be exhausted:

Rapid pressure changes may ruin the specimen.

Why must air exhaustion and readmission be gradual?

400–500 mm Hg

In the described vacuum embedding procedure, the negative pressure is approximately: