[Observation of the ultrastructure of smooth-muscle cells in the narrow segment of the ureter in children with congenital hydronephrosis].

The smooth-muscle cells of narrow segment in the ureter with congenital hydronephrosis in 5 cases were studied by transmission electron microscope. The result showed that the smooth-muscle cells of the narrow segment lack of myofilaments, dense body and dense patch in cells membrane. The above mentioned structures are functional deficient basis of the smooth-muscle cells in the ureter. Its deficiency results in the poor peristalsis function of the narrow segment of the ureter in congenital hydronephrosis. The cause and treatment principle in congenital hydronephrosis were discussed.