The renal collecting system after medullary damage.

The micromorphology of the renal collecting system after unilateral papillectomy in rabbits was investigated. Two weeks to six months after papillectomy, tubular micropuncture studies were performed. Cleared specimens were studied by light microscopy and microradiography. Histologic and physiologic correlations were made. At two to four weeks, the papillectomized kidneys were smaller and had smooth, mottled surfaces. At one to six months, there was cortical scarring with decreased concentrating ability. Ductal micropuncture revealed dilated collecting tubules and ducts which were obstructed at the papillectomy site. It is concluded that obstructed collecting ducts may be responsible for the cortical atrophy and are the primary cause of renal cortical damage after papillectomy in our model.