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Unit 5. Animal Reproduction. Sexual & Asexual Reproduction. Asexual Offspring all have same genes (clones) No variation Sexual Gametes (sperm & egg)  fertilization Mixing of genes  variation. Fertilization. Joining of egg & sperm External Usually aquatic animals Internal

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unit 5

Unit 5

Animal Reproduction

sexual asexual reproduction
Sexual & Asexual Reproduction
  • Asexual
    • Offspring all have same genes (clones)
    • No variation
  • Sexual
    • Gametes (sperm & egg)  fertilization
    • Mixing of genes  variation
fertilization
Fertilization
  • Joining of egg & sperm
    • External
      • Usually aquatic animals
    • Internal
      • Usually land animals
development
Development
  • External
    • Development in eggs
  • Internal
    • Placenta
      • Exchange food & waste
    • Live birth
adaptive advantages
Adaptive Advantages?
  • What is the adaptive value of each type of sexual reproduction
    • Number of eggs?
    • Level of parental of care
    • Habitat?
reproductive hormones
Reproductive Hormones
  • Testosterone
    • From testes
    • Functions
      • Sperm production
      • 2° sexual characteristics
  • Estrogen
    • From ovaries
    • Functions
      • Egg production
      • Prepare uterus for fertilized egg
      • 2° sexual characteristics
sex hormone control in males
Sex Hormone Control in Males

Hypothalamus

GnRH

Pituitary

FSH & LH

Testes

Testosterone

Body cells

male reproductive system
Male Reproductive System
  • Testicles
    • Produces sperm & hormones
  • Scrotum
    • Sac that holds testicles outside of body
  • Epididymis
    • Where sperm mature
  • Vas deferens
    • Tubes for sperm to travel from testes to penis
  • Prostate, seminal vesicles, Cowper’s (bulbourethal) glands
    • Nutrient rich fluid to feed & protect sperm
    • Buffer to counteract acids in vagina
spermatogenesis
Spermatogenesis

Testis

Epididymis

Germ cell

(diploid)

Coiled

seminiferous

tubules

spermatocyte

(diploid)

MEIOSIS I

spermatocytes

(haploid)

MEIOSIS II

Vas deferens

Spermatids

(haploid)

Spermatozoa

Cross-section of

seminiferous tubule

female reproductive system
Female Reproductive System
  • Ovaries
    • Produces eggs & hormones
  • Uterus
    • Nurtures fetus; lining builds up each month
  • Fallopian tubes
    • Tubes for eggs to travel from ovaries to uterus
  • Cervix
    • Ppening to uterus, dilates 10cm (4 inches) for birthing baby
  • Vagina
    • Birth canal for birthing baby
menstrual cycle

LH

Menstrual Cycle

FSH

Hypothalamus

egg development

ovulation = egg release

GnRH

corpus luteum

Pituitary

FSH & LH

estrogen

progesterone

Ovaries

lining of uterus

Estrogen

Body cells

days

0

7

14

21

28

egg maturation in ovary
Egg Maturation in Ovary
  • Corpus luteum
    • Produces progesterone to maintain uterine lining
female hormones
Female Hormones
  • FSH & LH
    • release from pituitary
    • stimulates egg development & hormone release
    • peak release = release of egg (ovulation)
  • Estrogen
    • released from ovary cells around developing egg
    • stimulates growth of lining of uterus
    • lowered levels = menstruation
  • Progesterone
    • released from “corpus luteum” in ovaries
      • cells that used to take care of developing egg
    • stimulates blood supply to lining of uterus
    • lowered levels = menstruation
oogenesis
Oogenesis
  • What is the advantage of this development system?

Meiosis 1 completed

during egg maturation

ovulation

Meiosis 2 completed

triggered by fertilization

fertilization17
Fertilization
  • Joining of sperm & egg
    • Sperm head enters egg
cleavage
Cleavage
  • Repeated mitotic divisions of zygote
    • 1st step to becoming multicellular
  • zygote  morula  blastula
gastrulation
Gastrulation
  • Establish 3 cell layers
    • Ectoderm
      • Outer layers
        • Skin, nails, teeth, nerves
    • Mesoderm
      • Blood, bone & muscle
    • Endoderm
      • Inner lining
        • Digestive system
placenta
Placenta
  • Materials exchange across membranes