Biology Reference
In-Depth Information
In addition to being an obvious clinical endpoint, a relatively
consistent degree of angiographic vasospasm can be produced in
animal models and the spasm can be measured reproducibly in a
variety of animal models (nonhuman primate, dog, rabbit, rat, and
mouse) using different methods (catheter angiography and histology)
(
6-9
). This chapter discusses histological image analysis for the
measurement of cross-sections of arteries.
Measurements of vasospastic arteries were described as early as
1979 using direct analog photography of the surgically exposed
arteries, as opposed to more conventional catheter angiography
(
10
). Vasospasm was assessed by measuring the area of a segment of
the artery. Subsequent modifi cations include quantitative measure-
ments of cross-sections of histologically stained arteries, electron
microscopy, and other imaging techniques to visualize the arteries
accurately in order to permit accurate measurements. For example,
Meguro et al. (
11
), used transmission electron microscopy (TEM)
and tracing imaging tools to measure artery lumen circumference
and radial artery wall tunica media plus intima thickness.
Currently, the gold standard for the measurement of artery
diameters probably is contrast angiography performed with adequate
resolution. However, quantitative measurements of histologically
prepared cross-sections of arteries correlate well with angiography
and require no radiology equipment so can be easier to perform.
The obvious disadvantage is that the animal has to be euthanized
to obtain the measurements so only one time point is obtained for
each animal (
3, 12
). Histology-based methods are relatively simple,
inexpensive and highly reproducible, providing an effi cient way to
measure the degree of vasospasm in experimental models.
2. Materials
and Instruments
2.1. Animal Perfusion
and Brain Removal
Saline fl ushing agent.
4% Paraformaldehyde in phosphate-buffered saline as a fi xative.
Perfusion setup.
Surgical instruments for performing perfusion and brain extraction.
Containers for brain preservation (volume should be ten times the
volume of the tissue to be fi xed.
To perform the sectioning, the following equipment is required:
2.2. Brain-Sectioning
Instruments
Rat or mouse brain matrix for coronal sectioning (1 mm thick
sections).
Steel back single-edged blades for brain slicing.
2.3. Paraffi nization
and Sectioning
Plastic cassettes to place tissue in.
Microtome.
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