Fig. 3

Functional relation between vessel diameter and endfoot area. Left: the proposed functional relations are based on quadratic (arteries, A) and linear (veins, V) functions such that the linear regression (LR) results from [6] are well-matched over the whole range of vessel diameters differentiating between arterial and venous vessels. The data from [6, Fig.2d, green solid line] corresponds to the data from 15-month-old mice; the data from [6, Fig.4c] (red and blue) to data from 12-month-old mice. No significant age-dependence of the endfoot area is observed by Wang et al. [6]. Dots show vessel-averaged data reported by Wang et al. [6, Fig.4c]. Average endfoot sizes, \(A^A\) and \(A^V\), for the endfoot sheath around arterial and venous vessels, respectively, are given in \(\upmu \hbox {m}^{2}\) for vessel radius (including endfoot sheath) \(r_{\textrm{o}}\) in \(\upmu \hbox {m}\). Right: average endfoot sizes, \(A^A\) and \(A^V\) estimated from the data [6] and corrected relation (computed with the presented theoretical model) accounting for the error inherent to the 2D image analysis