Comparative morphometric analysis of terminal vascularization of hippocampal CA1 and CA3 sectors in Mongolian gerbils

Comparative morphometric analysis of terminal vascularization (vessels with a diameter lower than 12.5 microns) in the ischemia-sensitive sector CA1 and the ischemia-resistant sector CA3 of Ammon's horn in Mongolian gerbils was performed. Basing on numerous computer-counted parameters characterizing the terminal vascular network in both hippocampal sectors and its relationship to the surrounding tissue, it was shown that a number of capillary vessels, their average diameter, and exchange and flow surfaces were to a statistically significant degree lower in the pyramidal layer of the CA1 sector as compared with those in CA3 sector. The number of pyramidal neurons in the pyramidal layer, counted per surface unit was in sector CA1 higher than in sector CA3. The obtained data indicate clearly an angioarchitectonically dependent lower microvascular capacity of sector CA1. However, these differences do not indicate per se a leading role of the vascular factor in the pathomechanism of selective vulnerability to ischemia. They may be a factor facilitating neuronal damage evoked by the excitotoxic action of glutamate, observed in CA1 sector as a result of forebrain ischemia.