Model of inverse permeability used to determine capillary functionality kinetics in a 3D culture.

<p>Texas Red-conjugated dextran (70 kDa) is added to the bulk gel for 30 minutes and allowed to freely diffuse. Early capillary sprouts, which lack mature cell-cell junctions between the endothelial cells that form the tubules, will easily allow the tracer to be transported from the tissue space into the interior of the capillary. By contrast, mature capillaries that are stabilized by pericytes and possess more mature cell-cell junctions are capable of excluding the tracer from the lumen.