Urothelial Smooth Muscle Cells (USMC)

The ureter is connected to the renal pelvis above and the bladder below, and is a pair of slender pipes that are flat and cylindrical in shape, with an average diameter of 0.5-0.7 centimeters. The total length of the adult ureter is 25-35 centimeters, located behind the peritoneum and vertically descending into the pelvis along the anterior side of the psoas major muscle. The ureteral wall is composed of three layers of tissue. The outermost fascia tissue surrounds the entire renal pelvis and ureter, with abundant blood vessels and nerve fibers; There are three layers of muscles in the middle, with the inner and outer layers being longitudinal muscles and the middle layer being circular muscles; The innermost layer is the mucosal layer, which is connected to the renal pelvis and bladder mucosa. The submucosal layer has abundant reticular lymphatic vessels, which are one of the pathways for infection in the kidneys and bladder. The physiological function of the ureter is to discharge urine from the renal pelvis into the bladder. The transportation of urine within the ureter is not a passive process, but is actively carried out through ureteral peristalsis. The ureter has a thick smooth muscle layer that can perform rhythmic peristalsis, allowing urine to continuously flow into the bladder. Therefore, the study of ureteral smooth muscle movement is an important research direction in urodynamics.