Abstract: Objective   To study the fiber architecture and distribution of smooth muscle in each segment of the ureter and provide morphological basis for the treatment of ureteral stones．Methods   Thirty fresh adult ureters were fixed by formalin with tissue sections to observe the morphology and distribution pattern of smooth muscle of the ureter under optical microscope The thickness and inner diameter of ureter smooth muscle by micrometer were measured.    Results    The smooth muscle at the beginning of the ureter was divided into four layers, and the maximum thickness of the smooth muscle was 1.59 mm on the left and 1.51 mm on the right. The maximum diameter on the left was 2.22 mm and 2.05 mm on the right. The abdominal smooth muscle was divided into three layers, and the left maximum thickness was 1.49 mm and 1.69 mm on the right. The smooth muscle in the ureter at the entrance of the small pelvis was divided into three layers, most of which were longitudinal muscle,the maximum thickness of smooth muscle on the left side was 2.38 mm, 1.98 mm on the right side. The inner diameter of the ureter was 2.11 mm on the left and 2.28 mm on the right. The ureter in the pelvic segment has four layers of smooth muscle, mostly longitudinal muscle and annular muscle, the maximum thickness of smooth muscle was 1.69 mm on the left and 1.58mm on the right.The smooth muscle of the inner wall segment was divided into three layers, the smooth muscle was the thickest, the maximum thickness on the left was 3.18mm and 3.21 mm on the right. The longitudinal muscle was the most developed, and the annular muscle was associated with the urethral sphincter. The ureteral inner diameter was 1.25 mm on the left and 1.70 mm on the right. The interrelationship between ureteral smooth muscle construction and urodynamics was discussed.   Conclusions   The main reason for the difficulty in the reduction of ureteral calculi may be related to the arrangement of longitudinal muscle and circular muscle of ureteral smooth muscle.

Key words: Ureter; ,  , Smooth muscle construction; ,  , Urodynamics; ,  , Ureteral stone