Mammalian Reproduction Part I MaleFemale Systems

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Mammalian ReproductionPart I Male/Female
Systems
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Evolution of Reproductive Characteristics

• Mammary glands
• Nourishment of newborn with milk
• Close mother-offspring bond
• Evolved in association WITH dyphylodont teeth
• Shared by Prototherians, Metatherians, and
  Eutherians

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Evolution of Reproductive Characteristics

• Viviparity probably evolved after nursing
• Lacking in Monotremes
• Monotremes have mammary glands
• Monotremes have close maternal bonds
• Evolution of these traits increases likelihood of
  offspring survival and success.

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Male Reproductive System

• General System
• Paired testes Sperm production
• Paired accessory glands Secretions
• Duct System Transport
• Copulatory Organ Delivery

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Male Reproductive System

• Prototherians
• Testes abdominal
• Penis located within sheath inside cloaca
• Urethra delivers semen only
• Urine is voided from urogenital sinus into cloaca
• Abdominal Testes Cetaceans, pinnipeds, elephant,
  some shrews, sirenians, anteaters, and hyraxes.

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Male Reproductive System

• Metatherians
• Testes are scrotal (except Notoryctes)
• Scrotum is anterior to penis
• Testes temperature regulated through rete network
• Difference between scrotum/body temp 1.4 6.5?C
• In high Ta Trichosurus can increase difference to
  14 ?C by licking scrotum.

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Male Reproductive System

• Metatherians
• Penis retained within cloaca
• Penis variable in structure
• Often bifurcated
• American forms prominently bifurcated
• Urethra extends as a groove along each segment of
  penis
• Macropodids penis is a bifurcated filiform
  structure

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Male Reproductive System

• Metatherians
• Sperm Binding
• New world marsupials
• Sperm are coupled at the head in epididymes
• Dont separate until in oviducts
• May increase sperm survival allowing less sperm
  production while maintaining sperm viability

F 10.9
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Male Reproductive System

• Eutherians
• Permanently scrotal testes
• Ungulates (artiodactyla, Perissodactyla),
  carnivores, primates
• Permanently Abdominal
• Edentates, many insectivores, cetaceans,
  sireneans, proboscidea, hyracoidea, some
  insectivores, some pinnipeds
• Seasonally Retracted
• Many rodents

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Male Reproductive System

• Many mammals have a bone in the penis (Baculum or
  Os Penis)
• All carnivores, most primates (not humans,
  whew!), most rodents, most bats, some
  insectivores
• Female has an analog, baubelum or os clitoris

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Baculum forms
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Male Reproductive System

• Monotremes
• Urogenital sinus common chamber for
  urine/waste/reproduction
• Cloaca common exit for urine, waste,
  reproduction
• Metatherians
• Urogenital Sinus/Cloaca
• Eutherians
• Complete separation of urine, digestive,
  reproductive tracts

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Female Reproductive System

• General System
• Paired Ovaries egg/hormone production
• Duct System
• Oviducts Fertilization
• Uterus/i Implantation/fetal nourishment
• Cervix junction of uterus/vagina
• Vagina Birth Canal

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Female Reproductive System

• Ovaries
• Polytocous give birth to many young (litters)
• Ovaries are textured like a berry (many
  follicles)
• Monotocous give birth to single young
• Ovaries smooth and oval
• Oddities
• Platypus only left ovary functional (as in
  birds)
• Both ovaries functional in echidnas and all other
  mammals

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Female Reproductive System

• Uterus
• Structure consists of two tubes that are fused
  together to varying degrees.
• Not fused
• Monotremes, marsupials, some eutherians
• Fused
• Most Eutherians

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Female Reproductive SystemUterus Fusion

• Duplex
• Two uteri, each with opening (cervix) to vagina
• Lagomorphs, rodents, aardvarks, hyraxes
• Bipartite
• Separate uteri, one opening (cervix) to vagina
• Cetaceans, most carnivores
• Bicornuate
• Y-shaped uterus with 2 horns and one stalk
• Simplex
• No separation between uterine horns, single
  opening
• Some bats, higher primates, xenarthrans

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Uterine Fusion Shapes
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Female Reproductive System

• Vagina
• Monotremes lacking, have urogenital sinus
• Metatherians
• Paired, both penetrated by male bifid penis.
• Bladder and vaginae enter urogenital sinus, then
  opens to cloaca
• Eutherians
• Single vagina

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Female Reproductive System
Monotremes Marsupials
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Female Reproductive System

• Estrous
• Period when ovulation occurs (heat)
• Often seasonal
• Monestrous or polyestrous
• Spontaneous regular, repeating cycle of
  ovulation
• Induced occurs following copulation
• Menstrual Cycle higher primates, can be
  receptive anytime.

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Female Reproductive System

• Fertilization
• Female enters estrous and is receptive to mating
• Uterus begins to swell, vagina enlarges, ovarion
  follicles grow
• Ova discharged late in cycle, entering fallopean
  tubes
• Successful mating occurs and egg is fertilized