Aim: This study was undertaken to investigate the renal changes associated with obstruction of the urinary tract in the fetal lamb early in gestation (50 days). It was also undertaken to determine if urinary tract obstruction proximal or distal to the urinary bladder would result in varying renal morphology.
Methods: Timed-gestation ewes at 50-days gestation were anaesthetised, and the lambs exposed. Males had their urethra and urachus ligated with a fine silastic tubing. Females had one ureter ligated with the same tubing. They were delivered at term and sacrificed. The kidneys were weighed, measured and processed for histological examination.
Results: Three lambs (2 males and 1 female) survived. All 5 kidneys were small (2.2+/-0.4g, normal 17.3+/-1.3g), and had lost their normal architecture. Microscopically, these kidneys had few glomeruli, a relative abundance of stroma with apparent nodular collections of tubules surrounded in some instances by a cuff of fibrous stromal tissue.
Conclusion: The morphologic features produced by urinary tract obstruction at 50-days gestation in the lamb resembled those normally associated with human cystic renal dysplasia. The site of the obstruction had no effect on the development of subsequent renal pathology.