The Male Reproductive System: Structure, Function, and Clinical Considerations

The Male Reproductive System

Overview

The male reproductive system is responsible for the production, maturation, and delivery of sperm, as well as the secretion of male sex hormones. It consists of primary and secondary sex organs, accessory glands, and external genitalia.

• Primary sex organ: Testes

• Reproductive tract: Epididymis, ductus (vas) deferens, spermatic cord, urethra

• Accessory sex glands: Seminal vesicles, prostate gland, bulbourethral glands

• External genitalia: Penis, scrotum

Components of the Male Reproductive System

Scrotum

The scrotum is an outpouching of loose skin and superficial fascia that houses and protects the testes.

• Regulates testicular temperature (lacks superficial fat, contains sweat glands)

• The left scrotum is typically lower than the right

• Contains the Dartos muscle for temperature regulation

Testes

The testes are paired, almond-shaped gonads suspended in the scrotum by the spermatic cord.

• Size: ~4 cm long, 2.5 cm wide, 10.5–14 g

• Functions:

  • Spermatogenesis: Production of sperm

  • Hormone production: Secretion of androgens, primarily testosterone

Common Abnormalities of the Testes

• Cryptorchidism: Failure of one or both testes to descend into the scrotum

Epididymis

The epididymis is a single, coiled tubule (~6 meters long) located on the superior and posterior-lateral margins of the testis.

• Divided into head, body, and tail (continuous with the ductus deferens)

• Functions:

  • Secretes and absorbs nourishing fluid

  • Recycles damaged spermatozoa

  • Stores spermatozoa for up to 2 weeks for maturation

Ductus (Vas) Deferens

The ductus deferens is a muscular tube (~45 cm long) that transports sperm from the epididymis to the ejaculatory duct.

• Runs through the spermatic cord and inguinal canal into the pelvic cavity

• Terminal part forms the ampulla, which joins the duct of the seminal vesicle to form the ejaculatory duct

Ejaculatory Duct

Formed by the union of the vas deferens and the duct of the seminal vesicle.

• ~2.5 cm long

• Opens into the prostatic urethra

• Drains seminal fluid into the prostatic urethra

Urethra

The urethra extends from the base of the urinary bladder to the tip of the penis and is divided into three regions:

• Prostatic urethra

• Membranous urethra

• Spongy (penile) urethra

Accessory Sex Glands

Seminal Vesicles

Paired, elongated glands located posterior and inferior to the urinary bladder, lateral to the vas deferens.

• Secrete ~60% of seminal fluid

Prostate Gland

The largest male accessory gland, walnut-sized, located below the neck of the bladder and traversed by the prostatic urethra.

• Secretes 20–30% of seminal fluid

• Produces enzymes (e.g., acid phosphatase) that:

  • Activate sperm motility

  • Degrade mucus

  • Provide antibiotic action

  • Neutralize acidity of urine and female reproductive tract (alkaline fluid)

Bulbourethral (Cowper’s) Glands

Small, paired glands at the base of the penis.

• Secrete alkaline mucus for neutralization of urinary acids and lubrication

Penis

Structure and Function

The penis serves as both a copulatory and excretory organ.

• Penile urethra transmits urine and seminal fluid

• Composed of three cylindrical masses of erectile tissue:

  • Two corpora cavernosa (primary erectile tissue, provide rigidity and length)

  • One corpus spongiosum (secondary erectile tissue, surrounds urethra, forms glans and bulb of penis)

Common Abnormalities of the Penis

• May include structural or vascular disorders (e.g., priapism, penile trauma)

Spermatogenesis

Sperm Structure and Production

Spermatogenesis is the process of sperm production, occurring in the seminiferous tubules of the testes.

• About 200 million sperm are produced daily

• Sperm structure:

  • Head: Contains nucleus and acrosome (enzymes for egg penetration)

  • Middle piece: Packed with mitochondria for energy

  • Tail: Flagellum for motility

Testosterone Production

Role and Effects of Testosterone

Testosterone is the principal androgen produced by the testes. It is essential for male reproductive function and the development of secondary sexual characteristics.

• Promotes maturation of spermatozoa

• Maintains accessory sex organs

• Responsible for secondary sexual characteristics (e.g., muscle mass, body hair, deep voice)

• Stimulates metabolic processes (protein synthesis, muscle and bone growth)

• Influences brain development, sexual drive, and behaviors

Nursing Assessment and Red Flag Symptoms

Nursing Assessment

• Pain

• Swelling or lumps

• Urinary changes

• Discharge or signs of infection

• Sexual function

Red Flag Symptoms

• Sudden testicular pain

• Urinary retention

• Blood in semen (haematospermia)

• Persistent erectile dysfunction

• Scrotal swelling with fever

Summary Table: Main Structures and Functions

Structure	Main Function(s)
Testes	Spermatogenesis, testosterone production
Epididymis	Sperm maturation and storage
Vas deferens	Transport of sperm
Seminal vesicles	Secretion of seminal fluid (nutrients for sperm)
Prostate gland	Secretion of enzymes, alkaline fluid
Bulbourethral glands	Secretion of mucus for lubrication
Penis	Copulation, excretion

Additional info:

• Testosterone also plays a role in erythropoiesis (red blood cell production) and influences mood and cognitive function.

• Cryptorchidism increases the risk of infertility and testicular cancer if not corrected.