ISSN:
1432-2307
Keywords:
Berry aneurysm
;
Medial defect
;
Medial muscle cell necrosis
;
Degeneration of internal elastic lamina
;
Cerebral arterial bifurcation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary It is a well known fact that the berry aneurysms, which are the direct cause of subarachnoid hemorrhage, develop at the apices of bifurcations of larger cerebral arteries. In order to elucidate the morphogenesis of the aneurysms in these sites, electron microscopic observation was made on one of their predilective regions, that is, the bifurcation of the first temporal branches from the middle cerebral arteries. Human autopsy cases from newborn and elderly patients were studied. The apices of the cerebral arterial bifurcations exhibited a medial defect immediately after birth, where collagen fibrils, ground substance and increased basement membrane-like substance were observed, suggesting that the defect might have resulted from necrosis of medial muscle cells. The tunica media adjacent to the defect became tapered into a wedge-like shape with the thin and towards the defect and the medial muscle cells were decreased in number. In young cases, medial muscle cells near the defect displayed focal cytoplasmic necrosis, and granulovesicular cell debris and lamellar increase of basement membrane-like substance were seen around the muscle cells with irregular profiles. With aging the defect gradually enlarged and the adjacent part of the media composed of lamellarly or reticularly increased basement membrane-like substance and granulovesicular cell debris, without muscle cells. In the media away from this area muscle cells were irregular and surrounded by granulovesicular cell debris, similarly increased basement membrane-like substance, and increased collagen fibrils, with enlarged intercellular spaces. The internal elastic lamina at the apices of bifurcations showed fragmentation and lumpy degradation both of which increased with age. Necrosis of medial muscle cells and subsequent enlargement of the medial defect together with degenerative changes in the internal elastic lamina, which are age-induced and presumed to be due to haemodynamic factors, are all considered to be important in the formation of berry aneurysms.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01102871
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