Regional differences in statistical geometry of endothelial dense granules in human extremity veins.

Objectives: Leg and arm human veins are exposed to different gravitational stresses. We investigated if there is difference in the amount and geometry of secretory vesicles in their endothelium.

Methods: Superficial small vein segments were removed during vascular operations for electromicroscopic analysis. Vesicular area/total endothelial cross-sectional area was determined by computer-based morphometry. Long and short axes of granule cross sections were measured by image analyzing software.

Results: Vesicular density in all samples was 2.26 ± 0.34%. There was no significant difference between the vesicular densities of upper extremity and leg. The shape of the vesicles was more frequently elongated in leg than in arm sections (p < 0.01).

Conclusions: The density of the vesicles does not depend on vascular region or orthostatic load. Ellipticity of these granules is significantly different in areas exposed to different gravitational stresses. This might contribute to the differences of thrombotic and hemodynamic properties of leg and upper body veins.