Arterial supply of limbic structures in the guinea pig

This study outlines the vascular territories of the cerebral arteries that originate from the Willis circle to supply limbic structures in the guinea pig brain. The entire cerebral vascular system was visualized in four preli minary experiments by performing superselective microangiographic studies w ith iodine contrast medium perfusion of the whole brain after in vitro isol ation according to a technique described previously (de Curtis et al. [1991 ] Hippocampus 1:341-354). Subsequently, the perfusion territory of the diff erent arteries that originate from the Willis circle was characterized afte r cannulation and perfusion of individual arteries with a gelatin solution that contained waterproof black ink. The analysis was performed by identify ing the brain regions that contained the black stain on 150-mu m-thick coro nal sections that were cut after brain fixation with paraformaldehyde for a t; least 1 week. The middle cerebral artery and the rostral and caudal post erior cerebral arteries supply the limbic cortices and some related subcort ical regions. In particular, large portions of the hippocampal formation ar e supplied by both the rostral posterior cerebral artery and the rostral br anch of the caudal posterior cerebral artery, whereas the ventral temporal part of the hippocampus is served exclusively by the rostral posterior cere bral artery. The amygdala, the periamygdaloid cortex, and the piriform cort ex are served by the middle cerebral artery and in part by the perforating arteries. The entorhinal, perirhinal, and postrhinal cortices are vasculari zed by the posterior and middle cerebral arteries, with a very broad overla p between the distal territories of these vessels. The demonstration of an extensive superimposition between the arterial supply of the entorhinal and the perirhinal regions suggests the presence of anastomotic connections th at potentially are protective against ischemic events. Such an arrangement was not observed for the arteries that supply the ventral portion of the hi ppocampal formation and the basolateral amygdala, which showed nonoverlappi ng boundaries. The pathophysiological consequences of a similar vascular or ganization are discussed. (C) 1999 Wiley-Liss, Inc.