| STUDYING
THE TEMPORAL BONE |
Before the organs of hearing
and balance can be studied the temporal bone must be run through several processing steps.
The steps to process a temporal bone include
fixation, decalcification, embedment, sectioning, staining and mounting. It takes an average of $2000 and up to 2 years to
prepare one temporal bone for study. Once processed, however, approximately 400 tissue
sections can be obtained from one temporal bone. These 400 sections can be divided to
produce 10 sets of the same temporal bone. This allows for more than one researcher to
study each bone while leaving some tissue sets for study using new techniques which might
be developed in the future.
The structures of the inner ear can be
prepared for a variety of research techniques, including microscopic study and procedures
that allow identification of hearing defects at the cellular and molecular level
("cellular and molecular biology").
Researchers examine each sample to learn more
about the ear structure and the causes of the donor's hearing or balance problem. Medical
records are also studied along with the temporal bone sections to understand the
relationship between actual hearing and structure within the temporal bone. With this
knowledge, researchers can develop new ways to diagnose and correct hearing and balance
disorders in others.
Processing One Set
of Temporal Bones
It takes an
average of $2000 and up to 2 years to prepare one temporal bone for study.
Once processed, however, approximately 400 tissue sections can be obtained
from one temporal bone. These 400 sections can be divided to produce 10 sets
of the same temporal bone. This allows for more than one researcher to study
each bone while leaving some tissue sets for study using new techniques
which might be developed in the future.
 |
One set of sections from one temporal
bone consists of 40 microscope slides.
Each section is only x/1000 of an inch
thick.
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PREPARATION OF
TEMPORAL BONE SPECIMENS FOR STUDY
Before the organs of the
hearing and balance system can be studied, the temporal bone must be run through several
processing steps. The result is 400 or more very thin sections of tissue which can be
examined under the microscope. |
1. Fixation
Immediately after removal, he small section of
temporal bone is be placed in a solution of chemicals which preserves the
tissue. The specimen remains in this solution for at least 48 hours. |
2. Decalcification
Because the organs of the hearing and balance system are
embedded inside the temporal bone the bony tissue must be removed. This is done by
dissolving the bony tissue in another solution for 30-40 days. |
3.
Embedment
The tissue which remains after decalcification is very soft.
This tissue must now be cut into very thin sections which made into microscope sides.
Before sectioning, the tissue must be embedded in a liquid which hardens into a
plastic-like material. This process takes several months. |
4.
Staining
Staining the sections allows for certain anatomical structures
to visualized better. Routine staining involves dipping the sections in series of
solutions such as the one below.
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5.
Sectioning & Mounting
Sectioning of the tissue is done on a specialized cutting
apparatus. The number of sections which can be obtained from one temporal bone ranges from
400-1000. This is possible because each section is only x/1000 of an inch thick!
Each section is mounted on one glass microscope slide and fixed in place with a thin
piece of glass as a cover and some tacking medium. |
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Examples of the horizontal planes
through the organs of hearing and balance.
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6.
The Finished Set of Temporal Bone Slides
A minimum of 10 nearly identical sets of temporal bone slides can be assembled
from the 400 or more slides obtained from one temporal bone. A finished set consists of 40
microscope slides made from taking every 10th slide from the 400 consecutive slides. Some
sets are prepared without staining so that they might be available for new staining
techniques developed in the future. |
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