Figure 1

Figure 1. Kidney innervation commences at E13.5 as axons follow the differentiating arteries and continue to branch throughout development. (A) Pan-neuronal labeling (TUBB3, green) of an E12.5 urogenital system (UGS) shows that renal nerves are absent in the kidney at E12.5 as shown by immunostaining of the branching ureteric bud (cytokeratin, yellow). Ganglion and some postganglionic nerve fibers track along the descending aorta shown by alpha-smooth muscle actin (SMA, magenta). (B) Pan-neuronal labeling (TUBB3, green) of an E13.5 UGS shows that axons begin to innervate the kidney following the SMA+ vascular mural cells (magenta) of the developing arteries (arrowheads, zoomed image). CD31 (yellow) highlights the extensive endothelial network that has formed but is yet to be coated with mural cells. (C) Axonal projections (TUBB3, green) continue to grow and branch following the developing arterial tree (SMA, magenta) at E16.5. Cytokeratin (yellow) marks the collecting duct system. Multiple axon bundles can be observed on an artery (arrowhead, zoomed image). (D) By E18.5, axons (TUBB3, green) have undergone extensive growth with the arterial tree (SMA, magenta) and additional interstitial branching as the nerves navigate towards and around kidney structures such as glomeruli (podocin, yellow; arrowhead, zoomed image).