Additional file 1. Montage image showing a large section of human spleen tissue stained for TH. TH + nerve fibers occurred mainly around the arterial vasculature and rarely in the white pulp (wp) or red pulp (rp). Sympathetic nerve bundles (nb) were occasionally seen in large arteries. Arrows indicate central arterioles. Montage was created by stitching multiple 10X images using an Olympus BX41 microscope equipped with an Olympus DP74 digital camera and cellSens Dimension software.