The Seminal Vesicles

The seminal vesicles (SEH-muh-nul VEH-si-kuls) are two small glands adjacent to the terminals of the vas deferens (see Figure 4.6). The seminal vesicles play an important role in male fertility by contributing to the formation of healthy semen and functional sperm (Zhang & Jin, 2007). These glands secrete an alkaline fluid that is rich in fructose. This secretion constitutes a major portion of the seminal fluid, perhaps as much as 70%, and its sugar component seems to contribute to sperm nutrition and motility (Gonzales, 2001). Up to this point in its journey from the testis, a sperm cell is transmitted through the elab­orate system of ducts by the continuous movement of cilia, tiny hairlike structures that line the inner walls of these tubes. Once stimulated by energy-giving secretions of the seminal vesicles, however, sperm propel themselves by the whiplike action of their own tails.