[Anatomic analysis of canine ureteral smooth muscle structure]

We have investigated the structure of canine middle ureteral smooth muscle anatomically. In a transverse section inner fibers appeared to be longitudinal and outer fibers appeared to be circular. In the parallel sections with the wall of longitudinal ureteral muscle, inner and outer fibers appeared to be oblique in a mesh structure. In parallel sections with the wall of helical ureteral muscle, fibers appeared to be longitudinal. Anatomical analysis showed that canine ureteral smooth muscle is entirely composed of spinal fibers in a mesh structure and that the helical muscle strip have continuous fibers though the inner fibers have a tendency to run longitudinally and the outer fibers circularly.