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Begins to exist when a sperm reaches the egg and burrows inside. This causes the zona pellucida to harden, preventing any other sperm from getting inside. This also causes the egg to go into Meiosis II.
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Fertilization
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pronuclei join together
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occurs when the nuclear membrane of the ovum disappears and the two sets of chromosomes join together.
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first round of mitosis (cleavage)
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second round of mitosis
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third round of mitosis
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64 cell embryo called a blastocyst
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Occurs when the zygote begins to divide more, before implantation.
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implantation
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ectopic pregnancy could occur (approximate time)
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hCG begins to be secreated
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disc with streak on the underside forms mesoderm
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neural tube forms
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first missed period
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heart begins to beat, arms & legs buds appear, yolk
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face plates forming
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cleft lip or palate may occur
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muscles form, bent neck, webbed hands and feet, segmented back
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fingers & toes separate, eyes & ears formed
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genitalia begins to differentiate, eyelids fuse, amnion surrounds fetus
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chorionic villi sampling could be performed
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Occurs when the baby begins to grow faster, bigger, and longer. Its organs also finish developing.
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amniocentesis could be performed
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eyes open, fat added under skin, head out of proportion to the body
