The Vasa Deferentia
Once the sperm cells have emerged from the collection tube, they enter a shorter and rather straight tube called vas deferens (plural: vasa deferentia). This tube leads from the scrotum into the abdomen. The lower portion of the vas deferens can be felt through the scrotal skin. Since it is so easily located, it can also easily be cut in a sterilization operation known as a vasectomy. Inside the abdomen the two vasa deferentia (one associated with each testicle) bend in a long curve and lead up to a point behind the urinary bladder where they become enlarged, each forming a sort of sac or storage compartment called ampulla (plural: ampullae). The sperm cells are moved to these storage compartments to await ejaculation. The ampullae join the ducts of two other saclike organs, the seminal vesicles, to form short and straight tubes called ejaculatory ducts. These ejaculatory ducts run inside the prostate gland and there join the urethra. Before entering the ejaculatory ducts, the sperm cells have only a limited capacity of moving by themselves. Instead, they are transported mainly by the movement of tiny hairlike structures inside the tubes and by muscular contractions. However, immediately upon ejaculation they begin to move very vigorously. This dramatic change is produced by several fluids from various sources which together make up the semen. Swimming in the semen, the sperm cells gain their full energy. |
