Male Reproductive System

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Chapter 17

• Male Reproductive System

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Two Major Functions of Testes

• Testes produce sperm (spermatogenesis)
• Production Site seminiferous tubules
• Testes also produce male hormones (testosterone)

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Delivery of Sperm to the Egg

• The duct system stores and transports sperm
• Delivery through reproductive tubules epididymis
  ? vas deferens ? urethra ? penis

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Delivery of Sperm to the Egg

• The seminal vesicles and prostate gland
  (accessory glands) produce most of the volume of
  semen
• The penis transfers
• sperm to the female

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Sperm Production

• Sperm development involves reduction in the
  number of chromosomes and in the structure of
  sperm cells
• Several cell divisions of mitosis and meiosis
• Purpose produce a large number of sperm with
  half the number of chromosomes of somatic cells
  (haploid)

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Male Reproductive Hormones

• Hormones
• Testosterone
• Source Interstitial (Leydig) cells in testes
• LH stimulates production of testosterone in
  interstitial (Leydig) cells
• FSH enhances sperm formation by Sertoli cells

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The Male Reproductive System

• Testosterone production is regulated by a
  negative feedback loop (see in class worksheet)

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The Male Reproductive System

• The hypothalamus (neurosecretory cells) releases
  gonadotropin-releasing hormone (GnRH)
• GnRH stimulates the anterior pituitary gland to
  secrete luteinizing hormone (LH)
• LH stimulates the production of testosterone by
  the testes

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The Male Reproductive System

• The rising testosterone level inhibits the
  release of GnRH to complete the loop

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Actions of Testosterone on Target Tissues

• Actions of Testosterone
• Controls growth and function of male reproductive
  tissues (e.g., prostate seminal vesicles)
• Secondary sexual characteristics muscle,
  auxiliary hair, larynx, balding pattern
• Stimulates aggression and sexual behavior

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