Fertilization: the early development

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Fertilization the early development

• Dr. Alfiah Hayati
• Biologi Unair

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Internal fertilization

• is a form of animal fertilization of an ovum by
  spermatozoon within the body of an inseminated
  animal, whether female or hermaphroditic

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• In mammals, internal fertilization is done
  through copulation
• Some other higher vertebrate animals (most
  reptiles, most birds, and some fish) reproduce
  internally, but their fertilization is cloacal

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Internal fertilization

1. Oviparous organisms, including most insects,
   reptiles, and all birds eggs ? develop ? laid
   and hatch later
2. Viviparous organisms, all mammals, developing ?
   within the female's reproductive tract
3. Oviviparous organisms, like the garter snake, and
   the Madagascar hissing cockroach, have eggs that
   hatch ? making it look like "live birth"

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External fertilization

• is a form of fertilization in which a is united
  with an egg cell external to the body of the
  female ? fertilization is said to occur
  "externally"

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• Sperm ? mobile in a watery environment, aquatic
  animals ? they live
• In many aquatic animals ? eggs and sperm are
  simultaneously shed into the water ? the sperm
  swim through the water to fertilize the egg
• In many fish species (salmon) ? female deposit
  unfertilized eggs in the substrate ? male will
  swim by and fertilize them

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Fertilization

• The major events of the first week of
  development
• a. cleavage, b. formation of
  the blastocyst, and c. the
  beginning of the implantation process
• 2. Fertilization can only occur after ovulation ?
  secondary oocyte ? ampulla of the uterine tube ?
  several hundred sperm

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• Human fertility depends on factors of
• - nutrition,
• - sexual behavior,
• - culture,
• - instinct,
• - endocrinology,
• - timing,
• - economics, and
• - emotions

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Female fertility

• The average age of menarche in the United States
  is about 12.5 years
• Women's fertility peaks between the ages of 22 to
  26 year
• At age 30, 75 will get pregnant within one year,
  and 91 within four years.
• At age 35, 66 will get pregnant within one year,
  and 84 within four years.
• At age 40, 44 will get pregnant within one year,
  and 64 within four years.13

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Male Fertility

• Erectile dysfunction increases with age (exp
  being fertile at 94 years old)
• Increased male age is associated with a decline
  in
• semen volume,
• sperm motility,
• sperm morphology
• Comparisons between men lt30 gt 50 found relative
  decreases in pregnancy rates between 23 and 38
• Sperm count declines with age (5080 years, 75
  compared 2050 years)

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• In males 2039 years old, 90 of the seminiferous
  tubules contain mature sperm.
• In males 4069 years old, 50 of the seminiferous
  tubules contain mature sperm.
• In males 80 years old and older, 10 of the
  seminiferous tubules contain mature sperm.

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Female infertility

• 1. problems with ovulation (premature ovarian
  failure and polycystic ovary syndrome PCOS)
• 2. the uterus may not be receptive to
  implantation
• 3. blocked fallopian tubes ? endometriosis,
  pelvic inflammatory disease, or surgery
• 4. physical problems with the uterine wall
• 5. lifestyle and environmental factors ? Age,
  Stress, Poor diet, overweight / underweight
• Smoking, drugs, and alcohol
• 6. Medication Environmental toxins and Genetic
  conditions
• 7. Other health problems, such as sexually
  transmitted diseases

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Male infertility

1. ability to have and sustain an erection, enough
   sperm, enough semen to carry the sperm to the egg
2. physical problems testes that don't make enough
   normal sperm, hormonal problems, and lifestyle
3. environmental factors age and stress
4. Exposing the testes to high temperatures
5. Cryptorchism is a condition where the testes do
   not descend into the scrotum ( the body cavity
   has a higher temperature than the external
   scrotum)
6. Smoking, drugs, and alcohol
7. Medications environmental toxins, genetic
   conditions, such as Klinefelter syndrome
8. Other health problems

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Wassalam