According to the sources, the human male reproductive system contains a specific sequence of ducts and glands. Label A represents the vas deferens, which is the duct that ascends to the abdomen and loops over the urinary bladder . Labels B, C, and D represent the male accessory glands: B is the seminal vesicle (paired), C is the prostate (single), and D is the bulbourethral gland (paired) . These glands are responsible for producing seminal plasma, which is rich in fructose and calcium .