Arterial vasa vasorum: a quantitative study in the rat.

This study was designed to quantitate the vasa vasorum of common iliac arteries in 20 rats. The number of vasa vasorum per mm2 of arterial wall was extremely variable - from 0 to 124, the mean being 33 . 95 +/- 29 . 86 (S.D.). There was no significant difference in the vasa vasorum vascularity between the right and left common iliac arteries. The mean wall thickness of these arteries was 0 . 085 +/- 0 . 015 (S.D.) mm and 60 +/- 8% (S.D.) of this was made up by the tunica media. Arterial tissue in this study was shown to have approximately 10% of the vascularity of muscle tissue. By relating these data to the 'critical depth' hypothesis, on the nutritional supply of large arteries, it was concluded that the vasa vasorum in the common iliac arteries in rat (major arteries in small animals) probably play an insignificant role in the nutrition of the arterial wall.