LESSON 2: ANIMAL REPRODUCTION

• Major organs in the male reproductive system

  • Testicles
  • Epididymis
  • Scrotum
  • Vas deferens
  • Urethra
  • Seminal vesicles
  • Prostate gland
  • Cowper's gland
  • Penis
• Testicles


  • Produce sperm or male sex cells (spermatozoa)
  • Produce testosterone hormone that gives masculine traits
• Epididymis


  Sperm cells are stored and mature here
• Scrotum


  • Two-lobed sac that contains and protects the testicles
  • Regulates the temperature of the testicles
• Vas deferens


  Transportation tube that carries sperm-containing fluid from epididymis to urethra
• Urethra


  Muscular canal extending from urinary bladder to end of penis
• Seminal vesicles


  Produce fluid that protects and transports sperm
• Prostate gland


  Produces fluid that mixes with seminal fluid during reproduction
• Cowper's gland


  Produces fluid that moves down urethra ahead of seminal fluid
• Penis


  • Deposits semen within female reproductive system
  • Urethra surrounded by spongy tissue that fills with blood during arousal, causing erection
• Major organs in the female reproductive system

  • Ovaries
  • Oviducts
  • Uterus
  • Vulva
  • Bladder
  • Clitoris
  • Vagina
• Ovaries


  Produce female sex hormones estrogen and progesterone
• Oviducts


  Carry ova from ovaries to uterus
• Uterus


  • Site where fetus grows until birth
  • Larger uterine horns and smaller body for species that produce more offspring
• Cervix


  Lower outlet of uterus, composed of connective tissue and mucosal cells
• Vulva


  External opening of reproductive and urinary systems
• Bladder


  Collects liquid waste (urine) which passes through urethra to vagina
• Clitoris


  Sensory and erectile organ that produces sexual stimulation during copulation
• Vagina


  Passage between cervix and vulva, serves as copulation and birth canal
• Asexual reproduction


  One individual produces genetically identical offspring
• Sexual reproduction


  Genetic material from two individuals is combined to produce genetically diverse offspring
• Advantages of asexual reproduction

  • Population can increase rapidly
  • Only one parent needed, more time and energy efficient
  • Faster than sexual reproduction
• Disadvantages of asexual reproduction

  • Offspring are clones, harmful mutations passed on
  • Shorter lifespans
  • Hard to control increasing population
  • Limited diversity
• Advantages of sexual reproduction

  • Increased genetic variability
  • Resilience to infectious diseases
  • Decreased genetic disorders
  • Increased evolutionary fitness
• Disadvantages of sexual reproduction

  • Time and effort to find mate
  • Fewer offspring produced
  • Reproduction not always successful
  • Favorable genes may not be passed down
• Stages of development


  1. Fertilization

  2. Cleavage

  3. Blastula

  4. Gastrula

  5. Organogenesis
• Fertilization


  Fusion of male gamete (sperm) and female gamete (ovum)
• Cleavage


  Mitotic cell divisions forming a compact mass called morula
• Blastula


  Hollow cluster of cells or blastomeres
• Gastrulation


  Germ layers become apparent and cell differentiation takes place
• Embryonic germ layers


  • Ectoderm
  • Endoderm
  • Mesoderm
• Organogenesis


  Organ formation during development