[Muscular tunic of the dog ureter in the normal state and in ureterohydronephrosis (data of scanning electron...

By means of scanning electron microscopy and macro- microscopical methods in 16 mongrel dogs the ureters have been studied, normal and at ureterohydronephrosis. The ureteral muscles are spirally shaped. The external muscular layer is oriented along the spiral, its step approximately corresponds to the length of the peristaltic wave. The spiral-shaped course of the muscular fasciculi in the middle layer is of opposite direction, the spiral step corresponds to the ureter diameter. The internal muscular layer is formed as a result of changes in the spiralization angle of the middle muscular layer from outside into inside. Fibrills of the connective tissue framework possess predominantly longitudinal orientation. At ureterohydronephrosis, together with increasing diameter of the ureter, the step of the muscular spiral decreases, the connective tissue fibrillar framework acquires a net-like structure.