Genitourinary Radiology > Embryology > Migration of the Kidney > Overview


Migration of the Kidney: Overview

 

  • Ascent in the Abdomen

    The metanephros begins its development in the upper sacral area during the 4th week of gestation, but with the rapid growth of the lumbar and sacral regions of the fetus, it migrates cephalad into the retroperitoneum of the upper abdomen.

    1. Horseshoe kidney
    2. Renal ectopia

  • Rotation

    Concommitant with the ascent into the abdomen, the kidneys undergo a medial rotation, bringing the ureteral pelvic junction to a medial position relative to the kidney.

  • Vasculature

    As the kidney ascends, it recruits and subsequently discards successively higher branches of the aortic artery for blood supply. The renal artery arises when it reaches its final position, usually branching from the aorta at the level of the second lumbar vertebra.

    1. Anomalous vasculature

      Renal vascular anomalies occur in up to 25% of adults. Most commonly, a second smaller artery supplies the lower pole of the kidney. In is not uncommon for there to be two or more arteries supplying the kidney, and for some of these to be branches of the iliac arteries. Abnormalities of renal vasculature are much more common with ectopic kidneys. Arterial anomalies are twice as common as venous anomalies.


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