Quantifying Capillary Distribution in Four Dimensions

Abstract

Capillary supply to tissue has for decades been quantified simply using capillary number, usually capillary density (CD), on the assumption that the intensity of point sources of oxygen in a section through any tissue will be a limiting factor for, or accurately reflect, the level of oxidative metabolism. This approach has met with limited success, being mainly applicable for highly aerobic tissue with a high CD and fairly regular geometry of the capillary bed. Many tissues, perhaps the majority, do not fall into this category, necessitating alternative approaches in order to provide an adequate description of capillary distribution as a basis for models of oxygen transport. However limitations are still evident. For example, estimates of overall capillary volume are available which exclude information at higher spatial resolutions, while powerful statistical treatments of point distributions often require unrealistic physiological assumptions.