Effect of urethral stenoses on the urinary tract

Intrauterine operations were carried out in fetal sheep varying from 50-122 days of gestation. Silk, catgut and polyglycolicacid sutures were used to produce varying degrees of stenosis. The urachus was ligated with a silk suture in all cases. Urachal ligation alone produces no ill effects on the upper urinary tract. The addition of urethral stenosis results in dilatation of the upper tract depending on the degree of infravesical obstruction. Partial ligation of the urethra produces a pyelocalyectasis which may disappear later. More severe degrees of obstruction are followed by hydronephrosis, hydroureter and megacystis. Dilatation begins in the region of the renal pelvis and proceeds in the antegrade manner towards the bladder. Histologically the parenchyma was reduced in thickness and showed dilated tubules. In the ureter and the bladder muscular hypertrophy was noticed. Depending on the time of the experiment, there was an increase of connective tissue within the ureter and bladder. In cases of extreme obstruction the ureter showed muscular atrophy. No infection, ureteral reflux, bladder diverticulosis, extravesicalisation of the ureter or narrowing of the ureter by hypertrophied musculature was seen. These experiments may throw some light on the pathogenesis of the megaureter syndrome occurring in childhood.