Morphometric analysis of the epineurial and endoneurial blood vessels of the human sciatic nerve in relation to aging

The aim of this research is to perform an analysis of the epineurial and endoneurial blood vessels in relation to aging. The research is conducted on samples of the human sciatic nerve of 12 case (age from 27 to 89). The histological sections are stained by streptavidin-biotin method of detecting the presence of Type IV collagen. After morphometric analysis the following stereological parameters have been calculated: the number of blood vessels per unit of area, the volume density of the blood vessels and the surface density of the blood vessels of the epineurium and endoneurium. An additional diameter measurement is performed for the endoneural blood vessels. In order to perform a more detailed analysis, the cases were classified into three age groups, the first (27-48 years), the second (49-70 years) and, the third (over 70 years). The bivariate correlation analysis showed that the number of blood vessels of the endoneurium, their volume and surface densities in relation to age produced a statistically significant positive correlation. One Way ANOVA test demonstrated a statistically significant increase in the number of endoneurial blood vessels in the age group III when compared the age group I and, in addition, it showed a significant decrease in the diameter of the age group II when compared to the age group I. Paired t - test shows a statistically significant higher number of endoneurial blood vessels in relation to the epineurial, namely, in the age group III. The volume and surface density of the epineurial blood vessels is significantly higher than the endoneurial in both the I and II age group. Age brings about significant changes of the endoneurial vascular network of the sciatic nerve due to the increase in density of the endoneurial blood vessels, their volume and surface densities. Consequently, in the cases older than 70 years, the number of endoneurial blood vessels significantly exceeds the number of epineurial blood vessels.