male reproductive system

Introduction: The male reproductive system produces, stores, and delivers sperm, and secretes hormones that regulate male physiology. This article explains the main organs involved, from the testes and scrotum to the ducts and accessory glands, and describes how sperm are formed, matured, and transported. You will learn how temperature regulation supports spermatogenesis, what each gland contributes to semen, and how the system integrates with the urinary tract. Illustrative images are included to show key structures. All information is drawn from publicly accessible, medically reviewed sources cited in the references.

Core organs and their anatomy

     Major structures include testes, epididymis, ducts, and glands

The function of the male reproductive system is to produce sperm and transfer them to the female reproductive tract. The paired testes are a crucial component in this process, as they produce both sperm and androgens, the hormones that support male reproductive physiology. In humans, the most important male androgen is testosterone. Several accessory organs and ducts aid the process of sperm maturation and transport the sperm and other seminal components to the penis, which delivers sperm to the female reproductive tract.

The structures of the male reproductive system include the testes, the epididymides, the penis, and the ducts and glands that produce and carry semen. Sperm exit the scrotum through the ductus deferens, which is bundled in the spermatic cord. The seminal vesicles and prostate gland add fluids to the sperm to create semen.

The testes are located in a skin-covered, highly pigmented, muscular sack called the scrotum that extends from the body behind the penis. This location is important in sperm production, which occurs within the testes, and proceeds more efficiently when the testes are kept 2 to 4°C below core body temperature.

The male reproductive system includes structures like the penis, scrotum, testicles, epididymis, seminal vesicles, and prostate. It plays a critical role in reproduction and sexual function.

• Testes: produce sperm and testosterone; housed in scrotum for temperature control.
• Epididymis: coiled tube where sperm mature; about 6 meters long if straightened.
• Ducts: ductus deferens carries sperm from epididymis to pelvic cavity.
• Accessory glands: seminal vesicles, prostate, and bulbourethral glands produce seminal fluid.

Sperm production, maturation, and delivery

Sperm travel from testes through ducts to urethra

Sperm are produced in testes via seminiferous tubules and stored in epididymis. The process involves ejaculation through the urethra, with seminal fluid added during transit.

From the lumen of the seminiferous tubules, the immotile sperm are surrounded by testicular fluid and moved to the epididymis, a coiled tube attached to the testis where newly formed sperm continue to mature. It takes an average of 12 days for sperm to move through the coils of the epididymis. As they are moved along the length of the epididymis, the sperm further mature and acquire the ability to move under their own power.

During ejaculation, sperm exit the tail of the epididymis and are pushed by smooth muscle contraction to the ductus deferens. The ductus deferens is a thick, muscular tube that is bundled together inside the scrotum with connective tissue, blood vessels, and nerves into a structure called the spermatic cord.

Sperm make up only 5 percent of the final volume of semen, the thick, milky fluid that the male ejaculates. The bulk of semen is produced by three critical accessory glands of the male reproductive system: the seminal vesicles, the prostate, and the bulbourethral glands.

As sperm pass through the ampulla of the ductus deferens at ejaculation, they mix with fluid from the associated seminal vesicle. The paired seminal vesicles are glands that contribute approximately 60 percent of the semen volume. Seminal vesicle fluid contains large amounts of fructose, which is used by the sperm mitochondria to generate ATP to allow movement through the female reproductive tract.

The paired ejaculatory ducts transport the seminal fluid into the next structure, the prostate gland. As shown in anatomical diagrams, the centrally located prostate gland sits anterior to the rectum at the base of the bladder surrounding the prostatic urethra. About the size of a walnut, the prostate is formed of both muscular and glandular tissues. It excretes an alkaline, milky fluid to the passing seminal fluid that is critical to first coagulate and then decoagulate the semen following ejaculation.

The final addition to semen is made by two bulbourethral glands that release a thick, salty fluid that lubricates the end of the urethra and the vagina, and helps to clean urine residues from the penile urethra.

• Production: spermatogenesis occurs in seminiferous tubules, continuous after puberty.
• Maturation: sperm gain motility during ∼12-day transit through epididymis.
• Delivery: muscular contractions move sperm through ductus deferens, ejaculatory ducts, and urethra, mixing with glandular fluids to form semen.

Related Topics

• Health
• Science
• Medicine

References

1. OpenStax. (n.d.). Anatomy and Physiology of the Male Reproductive System.
2. MedlinePlus. (n.d.). Male Reproductive System. U.S. National Library of Medicine.
3. MedlinePlus. (n.d.). Sperm release pathway. Medical Encyclopedia.