The ureter and the vas deferens are very different even though they are only one word. The ureter is a urinary organ that lies behind the abdominal cavity and descends vertically into the pelvis along the anterior aspect of the posterior aspect of the psoas major muscle. There are three narrowings of the ureter, the first at the renal pelvis and ureteral migrations, the second at the transiliac vessels, and the third into the interior of the bladder wall, and these narrowings are the sites where stones, blood clots, and necrotic tissue tend to rest. The urinary system consists mainly of the kidneys, ureters, bladder, and urethra. Urine produced by the kidneys is transported to the bladder through the ureters, which is why both men and women have them and they serve the same purpose of transporting urine from the kidneys to the bladder. The ureter connects to the renal pelvis on top and the bladder on the bottom. It is a pair of long, thin tubes, cylindrical in shape, with an average pore size of 0.5-0.7cm, and the total length of the ureter in an adult is about 25-35cm. The vas deferens is a male-specific organ of the reproductive system. The male reproductive system mainly consists of the testes, epididymis, vas deferens, seminal vesicle glands, prostate gland, etc. The testes produce sperm that passes through the vas deferens. Sperm produced by the testes are transported to the seminal vesicles through the vas deferens, so the vas deferens are male-specific and are the tubes that transport sperm. The vas deferens are a pair of elongated tubes, one on each side, with a total length of about 40 cm. one end of the vas deferens is connected to the epididymal ducts, and the other end joins with the ducts of the seminal vesicle glands to form the ejaculatory ducts, which open into the posterior urethra. In the scrotum, the testes produce sperm, which are stored by the epididymis. When a person is aroused to a certain level, the epididymis releases sperm, which flows from the vas deferens at the end into the urethra, where it mixes with prostate fluid to form semen.