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Fertilization
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Fertilized Egg
Begins to exist when sperm penetrates a woman's egg -
Pronuclei join together
12 Hours -
Zygote stage begins
Occurs when the male and female chromosomes fuse -
First Round of Mitosis (Cleavage)
30-36 Hours -
Second Round of Mitosis
40 hours -
Morula Formed
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Embryo Stage Begins
Occurs when the third cleavage (Morula) is formed -
Third Round of Mitosis
50-60 hours -
64 Cell Embryo Called a Blastocyst
4 Days -
Hatching Blastocyst
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Implantation
8-10 days -
Ectopic Pregnancy
Can happen during implantation -
HCG begins to be Secreted
12 Days -
Disc with Streak on the Underside forms Mesoder
12 Days -
Neural Tube Forms
14-22 Days -
First Missed Period
15 Days -
Heart Begins to Beat, Arm & Leg Buds Appear, Yolk Sac makes RBCs
21 Days -
Face Plates Form
34th, 35th, 36th Day -
Cleft Lip or Palate May Occur
34th, 35th, 36th Days -
Muscles Form, Bent Neck, Webbed Hands and Feet, Segmented Back
6th week -
Fingers & Toes Separate, Eyes & Ears formed
7 Weeks -
Genitalia Begins to Differentiate, Eyelids Fuse, Amnion Surrounds Fetus
50 Days -
Fetal stage begins
Occurs when the embryo experiences formation of all organs -
Chorionic Villi Sampling Could be Performed
9-11 Weeks -
Amniocentesis Could be Performed
14-15 Weeks -
Eyes Open, Fat added under skin, Head out of proportion to the body
6-7 months
