Experience with microaneurysm formation at the basilar terminus in the rabbit elastase aneurysm model.
OBJECTIVE
Intracranial aneurysms have been induced in mice, rats, rabbits, and primates through carotid artery ligation. We reviewed our experience with RCCA ligation to quantify the rate of aneurysm formation in rabbits.


METHODS
In 30 consecutive New Zealand white rabbits, the RCCA was ligated during surgery to create elastase-induced aneurysms. The basilar artery and its bifurcation were harvested at various time points after surgery, including 8 weeks (n = 5), 13 weeks (n = 3), 14 weeks (n = 2), 16 weeks (n = 4), 17 weeks (n = 4), 30 weeks (n = 6), and 33 weeks (n = 6). All specimens were embedded in paraffin and sectioned at 5 microm in a coronal orientation, to show the basilar bifurcation and its branches. All sections were stained with HE. After the sections were evaluated and the photomicrographs were taken, the sections were de-stained and re-stained with VVG staining for elastin.


RESULTS
The IEL was intact and continuous at the BT in all 30 rabbits, as was the medial layer. No bulge-like localized dilation, to suggest microaneurysm or nascent aneurysm formation, was observed at the BT in any subject. There were small (0.08 +/- 0.02 mm in diameter) concave structures along the P1 segments in 5 (16.7%) of 30 rabbits. On adjacent tissue sections, each of these 5 structures was shown to be branch vessels with intact IELs.


CONCLUSIONS
In our rabbit model, unilateral RCCA ligation does not induce microaneurysm formation.
Department of Radiology, Mayo Clinic, Rochester, MN 55905, USA.
D
D
Dai
Y H
YH
Ding
R
R
Kadirvel
D A
DA
Lewis
D F
DF
Kallmes
D015901:Angiography, Digital Subtraction; D000818:Animals; D001488:Basilar Artery / Q000000981:diagnostic imaging / Q000473:pathology; D002339:Carotid Arteries; D002533:Cerebral Angiography; D004195:Disease Models, Animal; D002532:Intracranial Aneurysm / Q000139:chemically induced* / Q000000981:diagnostic imaging / Q000473:pathology*; D008026:Ligation; D010196:Pancreatic Elastase / Q000494:pharmacology*; D011817:Rabbits; D017540:Tunica Media / Q000473:pathology
D010196:Pancreatic Elastase