Aim: Recent studies demonstrated that there is a correlation between cerebral asymmetry and paw preference. In addition, there is another hypothesis about relationship between vascularity of cerebral hemisphere, it is not investigated by morphometric studies. The aim of this study was to investigate the relation between cerebral asymmetry and paw preference by morphometric studies.

Material and Methods: Paw preference was determined by the food reaching test in Wistar rats, which their wheight avarage was 200-350 g. The movement of right and left paw was determined every day for totally ten days. The data of the paw preference was analysed by the statistical test, so the paw preference of each animal was found. After assessment of paw preference, the rats sacrificed and the brains were removed by craniotomy without separation of each hemisphere, and the whole brain was fixed in 10% formalin. After the tissues were performed routine paraffin embedding, 5 micrometer sections from the blocks were stained with Hematoxylene-Eosin. The volumes and lengths of the capillary of the cortex and the medulla in both hemispheres were estimated by Cavalieri techniques dependent on “blind basis” theory.

Results: There were a significant difference between two hemispheres with respect to capillary volume and lengths, while the volumes of the cortex and medulla was similar.

Conclusion: It was concluded that cortex asymmetry capillary was positive correlated with paw preference.