Intrarenal and extrarenal autonomic nervous system redefined

Purpose The autonomic nervous supply to the kidneys is involved in the development of several diseases including hypertension. The neural distribution at the segmental vessels and intrarenal vasculature has not been well characterized. Thus, we evaluated the autonomic nerve distribution from the great vessels to the renal cortex in a cadaveric model. Materials and Methods We performed a detailed anatomical nerve dissection from the inferior mesenteric artery to the renal operculum in 2 human cadaveric torsos. Autonomic nerve fibers were verified by dissecting the greater splanchnic, sympathetic trunk and ganglia. We then systematically cross-sectioned the kidneys in 12, 1 mm slices across 3.6 cm, and stained the slices for histopathological analysis of neural tissue in relation to segmental arteries and other anatomical landmarks. Advanced reconstructive software was used to create a 3-dimensional computer image. Results Autonomic nerve fibers are located almost exclusively anteriorly on the main renal arteries and segmental arteries, and are absent from veins. Histopathology revealed that the intrarenal nerves continued to track exclusively with the arteries but were more circumferentially distributed. There is minimal nerve tissue around the veins. Many nerves were within a few millimeters of the renal collecting system. Conclusions The autonomic nerves supplying the kidney maintain their distribution almost exclusively along the anterior surface of arteries as they pass from the aorta to the segmental arteries. Once inside the renal parenchyma, the nerves are circumferentially distributed around the renal arteries and are in close proximity to the renal collecting system.