The effects of exogenous epidermal growth factor on the developing urinary tract in rats: a stereological description

Abstract

Systemic treatment with epidermal growth factor (EGF) induces growth of all wall layers of the urinary tract in pigs and rats. In this study, we describe the time-dependent growth of the ureter and bladder. Forty-eight female Wistar rats were allocated into five groups receiving EGF treatment (150 μg/kg per day) for 0 (controls), 1, 2, 3 or 4 weeks before being killed. The 24-h urine excretion was increased only in the group treated for 4 weeks with EGF. Measured by a simple infusion device, EGF significantly increased the bladder capacity by more than 50% in all the EGF-treated groups. The volumes of the wall layers of the ureter and bladder were quantified using stereology. After 4 weeks of treatment with EGF, the total volumes of the ureter and bladder were 1.8- and 2.1-fold larger than in the control group (the urothelium was 2.8- and 3.5-fold larger and the muscular coat 1.6- and 1.6-fold larger in the ureter and bladder, respectively). In conclusion, the EGF-induced growth of the urinary tract is characterized by increased bladder capacity, and increased volume of all wall layers – most prominently the urothelium.