Morphology and distribution of GFP-positive perivascular mural cells of precapillary arterioles (Type 3 vessels).

Ramified and stellate-shaped GFP-positive mural cells with thin, branching processes (A) are distributed among DiI-perfused precapillary arterioles (B). Superposition of a z-stack of confocal images for GFP- and DiI-derived signals (C) demonstrates the perivascular position of GFP-positive mural cells. Mural cells are spaced widely along the vessel walls with their processes sparsely distributed on the vessel surface, and are loosely oriented in longitudinal and circumferential directions along the vessels. A single frame confocal image through an arteriole (D) demonstrates that only a small fraction of the surface area of vessel is covered by the thin branching mural cell processes (arrowheads). Scale bar = 20 µm.