Stereological analysis of the vascular network in superior colliculi

Abstract

Background/Aim: Superior colliculi have an important role in the visual system, some motor functions and behaviour. Branches of the posterior cerebral artery and surrounding vessels form a collicular arterial network, which gives rise to several penetrating vessels for superior colliculi. The aim of the study was to determine relative stereological parameters (volume, surface and length density) of the vascular network in superior colliculi and to correlate those parameters with age. Methods: Ten adult brainstems, both male and female, were cut transversally at the middle of superior colliculi in three-millimetre-thick strata. Every stratum was cut in 4 µm thick semiserial sections stained with Mallory method. Images of every fifth section (5, 10, 15, 20) of superior colliculus were taken with "Leica" DM 1000 microscope and "Leica" MC 170HD camera under x 400 magnification and analysed by ImageJ software with A 100 grid. Statistical analysis was performed by the SPSS software with 5 % level of significance using methods of descriptive statistics, Spearman's and Pearson's correlation coefficient. Results: The average volume density of vascular network in superior colliculi was 0.0203 mm 0 , surface density 6.133 mm-1 , and length density 205.357 mm-2. All those parameters decreased with ageing, but statistically significant change was seen only in length density (p = 0.006). Conclusion: Compared to the structures at the same transversal level, the vascular network of superior colliculi has an average density. With ageing, blood vessels become less tortuous.