Reproductive System

• Functions of the reproductive system

  • Production of gametes
  • Fertilization
  • Development and nourishment of a new individual
  • Production of reproductive hormones
• Gametes


  Sex cells formed in the testes and ovaries
• Formation of gametes


  Meiosis
• Components of the male reproductive system

  • Testes
  • Ducts (epididymis, vas deferens, urethra)
  • Accessory glands (seminal vesicles, prostate gland, bulbourethral glands)
  • Supporting structures (scrotum, penis)
• Testes


  • Located outside the body cavity in the scrotum
  • Temperature is below normal body temperature for normal sperm development
• Sperm development and transport

  1. Produced in testes

  2. Travel through ducts (ductus deferens, urethra) to exit the body
• Scrotum


  A saclike structure containing the testes, divided into right and left internal compartments
• Regulation of testicular temperature

  1. Dartos muscle contracts in cold weather to make scrotum firm and wrinkled

  2. Cremaster muscle pulls testes closer to body to increase temperature
• Seminiferous tubules


  • Site of sperm cell development
  • Contain germ cells and Sertoli cells
• Interstitial cells (Leydig cells)


  Endocrine cells that secrete testosterone
• Spermatogenesis


  Begins at puberty as interstitial cells increase and seminiferous tubules enlarge
• Ducts transporting sperm


  • Seminiferous tubules
  • Rete testis
  • Efferent ductules
  • Epididymis
  • Ductus deferens
• Epididymis


  A tightly coiled series of tubules where sperm cells continue to mature and develop the capacity to swim and bind to the oocyte
• Capacitation


  Final changes in sperm cells that occur after ejaculation into the vagina and prior to fertilization
• Ductus deferens (vas deferens)


  Transports sperm from the epididymis, forms part of the spermatic cord
• Transport of sperm through ductus deferens

  Smooth muscle contracts in peristaltic waves to propel sperm
• Seminal vesicle


  Sac-shaped gland that joins with the ampulla of the ductus deferens to form the ejaculatory duct
• Ejaculatory duct


  Duct formed by the joining of the seminal vesicle duct and ampulla of the ductus deferens, extends into the prostate gland and joins the urethra
• Parts of the urethra

  • Prostatic urethra
  • Membranous urethra
  • Spongy urethra
• Urethra


  Passageway for both urine and male reproductive fluids, but they do not exit at the same time due to a sympathetic reflex that contracts the internal urinary sphincter when reproductive fluids are passing through
• Ejaculatory duct formation


  1. Seminal vesicles and ampulla of ductus deferens join to form the ejaculatory duct

  2. Ejaculatory duct extends into the prostate gland and ends by joining the urethra within the prostate gland
• Parts of the male urethra

  • Prostatic urethra
  • Membranous urethra
  • Spongy urethra
• Urethra


  Passageway for both urine and male reproductive fluids
• Urine and reproductive fluids in the urethra

  • Do not exit the urethra at the same time
  • Sympathetic reflex causes internal urinary sphincter to contract, keeping semen from passing into the urinary bladder and preventing urine from entering the urethra
• Penis


  Male organ of copulation that functions in the transfer of sperm cells from the male to the female
• Penis


  • 3 columns of erectile tissue
  • Engorgement of erectile tissue with blood causes the penis to enlarge and become firm, a process called erection
• Erectile tissue columns of the penis

  • Corpora cavernosa (dorsal and sides)
  • Corpus spongiosum (ventral)
• Corpus spongiosum


  • Expands over the distal end of the penis to form the glans penis
  • Spongy urethra passes through it and opens to the exterior as the external urethral orifice
• Skin of the penis


  • Loosely attached to connective tissue at the shaft
  • Firmly attached at the base of the glans penis
  • Tightly covers the glans penis
  • Well supplied with sensory receptors, especially on the glans penis
• Prepuce (foreskin)


  Loose fold of skin that covers the glans penis
• Male reproductive glands


  • Seminal vesicles
  • Prostate
  • Bulbourethral (Cowper's) glands
• Seminal vesicles


  • Saclike structures located next to the ampulla of the ductus deferens
  • Two in number
  • Each joins the ampulla to form the ejaculatory duct
• Prostate gland


  • Consists of glandular and muscular tissue
  • Surrounds the urethra and ejaculatory ducts
  • Secretes prostatic fluid through 10-20 short ducts into the prostatic urethra
• Bulbourethral (Cowper's) glands


  • Pair of small, mucus-secreting glands located near the base of the penis
  • Duct from each gland enters the urethra
• Components of semen


  • Sperm cells (5%)
  • Seminal vesicle secretions (60%)
  • Prostate secretions (30%)
  • Bulbourethral gland secretions (5%)
• Functions of mucus in the urethra

  • Lubrication
  • Neutralization of acidity
  • Lubrication during intercourse
  • Reduction of vaginal acidity
• Functions of seminal vesicle secretions

  • Nourish sperm cells
  • Help thicken semen to keep sperm in the vagina longer
  • Contain enzymes that destroy abnormal sperm cells
  • Contain prostaglandins that stimulate smooth muscle contractions in the female reproductive tract to propel sperm
• Functions of prostate secretions

  • Regulate pH to neutralize acidity and provide optimal environment for sperm
  • Liquefy coagulated semen to release sperm cells
• Normal semen volume is 2-5 milliliters, containing about 100 million sperm cells per milliliter
• Regulation of male reproduction

  • Hormonal mechanisms control development of reproductive structures, secondary sexual characteristics, spermatogenesis, and aspects of sexual behavior
  • Neural mechanisms primarily control the sexual act and expression of sexual behavior