Morphological Assessments of Cerebral Vasospasm - Animal Models of Acute Neurological Injuries: Injury and Mechanistic Assessments - page 443

(b) Perfusion solution before fi xative solution.
Physiological saline.

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Ringer solution.

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(c) Fixative solution.
Several fi xative solutions in buffer have been used for fi xation
of cerebral arteries as follows. All of solutions can be used for
both light microscopy and electron microscopy.
2.5% Glutaraldehyde in 0.1 M sodium cacodylate buffer ( 1 ).

4% Paraformaldehyde in 0.1 M phosphate buffer (pH

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7.4) ( 2 ).
1% Glutaraldehyde and 4% formaldehyde in phosphate-

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buffered saline (pH 7.4) ( 3 ).
10% Formalin (formaldehyde) ( 4 ).

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All of buffer solution can be kept at room temperature and are
not harmful. All of fi xative solution, such as glutaraldehyde, para-
formaldehyde, and formaldehyde should be kept at 4°C and are
harmful for inhalation and contact.

3. Methods

1. Position (Fig. 1 ):
The animal is placed in a supine position. Position of neck
should be kept at physiological angle. Neck super-extension
should be avoided, since it causes stretch and compression of
the basilar artery between the pons and clivus, which cause it
fi xed as transformed appearance.
2. Perfusion fi xation (Figs. 2 and 3 ):
The bag with heparinized saline or phosphate buffer, the bag
with fi xative solution, the tube, and the cannula inserted into
the ascending aorta are connected and prepared for perfusion
(Fig. 2 ). The notch should be placed at the cannula tip. The
position of solution surface in the bag should be set at height
from the animal heart that is expected as perfusion pressure.
Under deep analgesia and anesthesia or after euthanasia (see
Note 1), thoracotomy is performed by skin incision from upper
limb of breast bone to epigastrium followed by cutting of midline
of breast bone or left costae near the breast bone. Lung is pressed
laterally, and the pericardium is widely opened. At fi rst, the ascend-
ing aorta is exposed and the aorta should be loosely coiled with
thread (*1). During this procedure, injury of aorta wall should be
avoided, since its injury prohibits effective perfusion of fl uid due to
leakage of fl uid. After that, the descending aorta is taken, if you
require its cramped during perfusion fi xation.

3.1. Perfusion Fixation