Fluorescence images of P2X3 receptor expression in urothelium (A, E), suburothelial plexus in bladder trigone or neck (B, F), detrusor (C, G) and serosa (D, H) from postnatal rats, P2-P7. For all images, exposure times were held constant. Expression of P2X3 receptor in the detrusor and serosa was relatively constant. On occasion, isolated or small groups of P2X3-IR cells were observed in close proximity or adjacent to detrusor smooth muscle (C, arrows). P2X3 receptor expression was weak in urothelial cells and sparse P2X3-IR was observed in the suburothelial plexus from P0-P14. Calibration bar represents 50 μm.