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Fertilization
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Fertilized Egg
Begins to exist when sperm enters the egg -
pronuclei join together
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Zygote Stage Begins
Occurs when the pronuclei join together -
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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Embryo Stage Begins
occurs after third mitosis -
morula forms
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hatching
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64 cell embryo called a blastocyst forms
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ectopic pregnancy could occur
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implantation
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disk with streak on the underside forms the mesoderm
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hCG begins to be secreted
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neural tube forms
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first missed period
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heart begins to beat, arm and leg buds appear, yolk sac makes RBCs
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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 and toes separate, eyes and ears form
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genetalia begins to differentiate, eyelids fuse, amnion surrounds fetus
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Fetal Stage Begins
occurs when genetalia begins to differentiate -
chorionic villi sampling could be performed
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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
