Development of the renal interstitium

The kidney is derived from two tissue sources and develops through a series of mesenchymal-epithelial transitions and epithelial-mesenchymal interacti ons to form an epithelial tubular organ embedded in an interstitium derived from mesenchyme. The primary interstitium of the embryonic kidney undergoe s significant differentiation to form the adult counterpart whose diverse c ells have structural and functional characteristics that relate to their lo cal milieu. Whether the adult interstitial cells retain the capacity to tra nsform to other cell types and thus play a role in pathophysiological condi tions appears more and more likely as the plasticity of cells becomes appar ent. Besides forming the adult interstitium, the primary interstitium is ac tive in metanephric development, with specific roles in nephron growth and collecting duct growth and arborization. Interruptions to the development o f the interstitium or amelioration of its developmental capacity result in severely disrupted kidneys. The development of the renal interstitium is an essential component in the process of renal genesis.