Meiosis

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Meiosis
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Fertilization
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Embryonic Development

• early development of an organism
• within 2 months of fertilization
• zygote undergoes mitosis (many times)

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• After a week, a ball of cells forms (morula)
• After the second week, hollow ball of cells forms
  (blastula)
• Cells are now embryonic stem cells (can grow into
  other types of cells

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• Blastula organizes into 3 layers
• Layers eventually forms organs

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Fetal Development

• Differentiation - process in which layers
• form organs
• Divided into three periods (trimesters)
• Each around 3 months long

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First Trimester

• 4 weeks brain and spinal cord
• 8 weeks bones cells
• embryo now called fetus
• 12 weeks organ systems
• Abortion can happen in first trimester

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6 weeks
12 weeks
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Second Trimester

• 12 to 16 weeks rapid growth
• 20 to 24 weeks growth slow
• fetus starts moving

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14 weeks
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20 weeks
24 weeks
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Third Trimester

• Continued growth (esp. brain)
• 32 weeks fat deposited

32 weeks