Reproductive System

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Reproductive System

• Gonads develop from genital ridges of mesoderm,
  just medial to kidneys
• Germinal epithelium will form the gametes

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Male - Testes

• Seminiferous tubules are coiled tubules lined
  with germinal epithelium make sperm in most
  vertebrates
• A few fish, cyclostomes, urodeles lack
  seminiferous tubules and make sperm in cysts that
  collapse upon spawning

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Location of testes

• Abdominal cavity in monotremes, elephants, whales
  and non-mammals
• Descended permanently in ungulates, carnivores,
  humans
• Rectractile in rabbits, lower primates

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Testes

• Sperm pass through the vasa efferentia in a
  closed system to the
• Vas deferens spermatic duct mesonephric duct

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• Vas deferens empties into cloaca below placental
  mammals and
• Urethra Urogenital sinus in placental mammals

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Copulatory Organs

• Needed to introduce sperm into females for
  internal fertilization
• Claspers in elasmobranchs modified pelvic fin

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Copulatory Organs

• Gonopodium teleosts modified anal fin

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Copulatory Organ

• Hemipenes in snakes and lizards
• Can protrude

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Copulatory Organs

• Penis
• Erectile tissue
• Turtles, crocodiles, monotremes, some birds have
  a penis as a thickening on floor of cloaca
• Placenta mammals have an external penis

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Female Gonad - Ovary

• Hollow, but lined with germinal epithelium in
  teleosts

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Ovary

• Thin-walled sacs in anurans and urodeles
• Fluid-filled lacunae in reptiles, bird,
  monotremes
• Solid in mammals, containing follicles

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Ovulation

• Into coelom, open system

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Oviducts, Uterus, Vagina

• Develop from Muellerian Ducts in most

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Oviducts, Uterus, Vagina

• Empty into cloaca below placental mammals
• May be specialized in some areas

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Hen
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Placental mammals

• Uterus variations
• Marsupials have 2
• Most placental mammals have horns for multiple
  births
• Cervix caudal-most muscular opening to vagina

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Placental Mammals

• Vagina
• The vagina, a cloacal derivative, empties into
  the urogenital sinus in most placental mammals
• The vagina opens directly to the vulva in rodents
  and primates

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Cloaca

• The cloaca, or vent, receives intestine and
  urogenital structures in all vertebrates except
  placental mammals

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Cloaca

• Urorectal fold is present in reptiles, birds and
  monotremes
• It begins to divide the cloaca
• Coprodeum collects digestive waste dorsally
• Urodeum collects urine ventrally
• Proctodeum common, undivided, terminal

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Cloaca

• Cloaca divides into urogenital sinus and rectum
  in all placental mammals except female primates
  rodents
• Urethra, vagina, rectum in female primates
  rodents

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Key Points

• Is the cloaca a correct term to use when
  discussing the mammal? Why or why not?

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Key Points

• What is meant by the reproductive system in the
  male being a closed system and the female being
  an open system?

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Key Point

• Gonads make gametes. Name the gonads and gametes
  for each sex.