Fixation and Tissue Processing.

Title of Activity 4?

Fixation not only preserves tissues by stopping autolytic changes but allows tissues to remain unchanged by subsequent treatment.

Fixation should be performed immediately since delay permits _____ and _____.

There are number of factors that will affect the fixation process:

Considered the best fixative for pathological specimens.

Give 4 reasons why Ten percent buffered neutral formalin is considered the best fixative for pathological specimens.

Formula/Solution of 10% buffered neutral formalin

Store in properly labeled container, Label as ____ chemical.

In the fixative 10% buffered neutral formalin, the specimen should be completely submerged in?

3 functions on why it is important to fix the tissues.

Title of Activity of 5?

Longest part in routine histopathology, done after proper fixation and before the staining process.

Sequential steps designed to remove the extractable water from tissue specimens and replace it with a medium that solidifies to allow sectioning.

Routine processing schedule adds two changes of formalin, to deal with

Tissue sections should be thin enough (______) to fit the dimensions of a standard cassette

Minute and few fragmented tissues should be wrapped in?

Cassettes should not be packed tightly into the processing baskets, To have

Don’t forget to have an accompanying worksheet in each run, listing the number of cassettes and their labels for?

What is dehydration?

The specimens in tissue cassettes are subjected to a series of ____________ of water miscible fluids progressively replacing the free water.

It prepares the tissues to be enveloped in a medium (paraffin wax) which is not miscible in water.

The most commonly used dehydration method?

Dehydration from aqueous fixatives commences in ______ ethanol, progressing through _____ ethanol, then ____ changes of absolute ethanol before proceeding to the clearing stage.

May cause hard, brittle, or shrunken tissues?

The most common processing problem, prevents access of the clearing agents into the tissue, making the specimen soft and non-receptive to wax infiltration.

Are the usual choice for dehydration. Routine use of graded alcohols from a lower to a higher concentration is standard.

What is clearing?

€�. Clearing agents in this step make the tissues _____ due to their relatively _____, thus the term “____.”

This is used to mark the endpoint and duration of the clearing step.

The presence of _____ indicates incomplete dehydration

Prolonged clearing time causes the tissue to become

Results in uneven hematoxylin- and eosin-staining and poor nuclear chromatin patterns.

One of the many clearing agents, is generally used for routine paraffin embedding because of its compatibility with many types and sizes of tissue specimens.

What is infiltration?

Infiltrating media must fill all spaces within the tissue to support section cutting.

For routine paraffin infiltration, commercially available paraffins are used. Paraffin wax turns liquid at (melting point)

Paraffin wax solidifies upon cooling down to?

Automatic tissue processors enhance the processing of tissue specimens by using:

This effectively allows the reagents to come in contact and diffuse throughout the surface area of the sections in cassettes

Tissue cassettes should be loosely packed in containers or baskets immersed in processing fluid having a specimen-volume-ratio of at least?

Heat raises the ______ and ______ and lowers the _____.

The application of mild heat within the range of ______ during the dehydration and clearing steps considerably reduces the processing time but may increase tissue shrinkage.

Applied during dehydration, clearing, and infiltration improves the quality of processing.