Aim: 

The aim of this study was to investigate the geometric characteristics of pial microcirculation in obese zucker rats (OZR). These vessels contribute to an adequate cerebral blood flow supply because previous studies reported that the OZR cerebral arterioles present a structural limitation of maximum perfusion capacity.

Methods: 

Male OZR were used to visualize pial microcirculation by a fluorescent microscopy technique through an open cranial window. The arteriolar network was mapped by stop-frame images. Diameters and lengths of pial arterioles were measured with a computer-assisted method and classified by Strahler's scheme. Arteriolar segments and elements were used to express the series-parallel features of the pial arteriolar networks. A connectivity matrix was utilized to describe the connection of blood vessels.

Results: 

The pial networks were organized in four arteriolar orders compared with the five orders detected in normal rats. The segments/elements ratio was the highest in order 4 arterioles, diminishing in lower arteriolar orders, thus indicating that asymmetry of bifurcations was the highest in the largest vessels. The connectivity matrix showed that order 4 arterioles gave origin to most order 1 and 2 arterioles.

Conclusion: 

The geometric characteristics of rat pial microcirculation indicated that the vessel distribution was fractal as in normal rats. However, the connectivity matrix proved that order 4 arterioles predominantly originated order 2 and 1 arterioles resulting in several anastomotic vessels.