CSEP421 - Reproductive System 1 (13.1)

Male Reproductive System

Objectives

• Name selected components of the male reproductive system.
• Briefly describe the functions of each component of the male reproductive system.

Testes

• Paired, oval glands located in the scrotum.
• Contain seminiferous tubules where sperm cells are produced.
• Secrete the hormone testosterone.

Scrotum

• A muscular pouch with two sacs, each containing a single testis.
• Muscles in the scrotum:
  • Contract to lift the testes up against the body (helps retain heat).
  • Relax to drop testes away from the body (helps lose heat).
• Sperm production requires a temperature of about 35^\circ C, which is 2^\circ C below core body temperature.

Epididymis

• Stores sperm while they mature.
• Contains smooth muscle in its walls, which propels sperm into the ductus deferens.

Ductus Deferens (Vas Deferens)

• Has smooth muscle in its wall.
• Propels sperm from the epididymis to the ejaculatory duct during ejaculation.
• Vasectomy: cutting and tying off the vas deferens to cause infertility, preventing sperm from passing through.

Seminal Vesicles

• Two seminal vesicles.
• Produce fluid which mixes with sperm at the end of the ductus deferens to form semen.

Ejaculatory Duct

• Carries semen from the ductus deferens to the urethra.
• Located within the prostate gland.

Prostate Gland

• Produces fluid which mixes with sperm to form semen.

Bulbourethral Glands

• Two bulbourethral glands.
• Secrete alkaline mucus into the urethra.
• Lubricates the urethra ahead of the ejaculate.
• Neutralizes acids (from urine) remaining in the urethra.

Urethra

• Has smooth muscle in its walls, which contracts to propel semen along the length of the penis during ejaculation.
• Carries urine out of the bladder during urination.

Penis

• Contains chambers that fill with blood to produce an erection.
• Delivers semen into the vagina during ejaculation.

Prepuce (Foreskin)

• Protects the head of the penis.
• May be removed through circumcision.

Sperm Cell Structure

• Head
  • Nucleus: contains 23 chromosomes.
  • Acrosome: cap-like vesicle filled with enzymes that help a sperm to penetrate an oocyte.
• Tail
  • Middle piece: contains mitochondria which provide energy.
  • Principal piece: longest portion of tail.
• Once ejaculated, sperm do not usually survive more than 48 hours in the female reproductive tract.