-
Start
Fertilization -
Fertilized Egg
Begins to exist when the sperm penetrates the cell membrane and enters the egg (fertilization). -
12 Hours
Pronuclei Join Together -
Zygote Stage Begins
Occurs when the mother's and the father's chromosomes come together to form the baby's genetic makeup in one cell nucleus. -
30-36 Hours
First Round of Mitosis (Cleavage) -
40 Hours
Second Round of Mitosis -
Hour 50-60
Third Round of Mitosis -
Morula Formed
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Embryo Stage Begins
Occurs when the baby becomes a morula. -
Hatching
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Day 4
64 Cell Embryo Called a Blastocyst -
Day 8-10
Implantation -
Day 10
Ectopic Pregnancy Could Occur -
Day 12
hCG Begins to be Secreted -
Day 12
Disc with Streak on the Underside Forms Mesoderm -
Day 14-22
Neural Tube Forms -
Day 15
First Missed Period -
Day 21
Heart Begins to Beat, Arm and Leg Buds Appear, and Yolk Sac Makes RBCs -
Day 34-36
Cleft Lip or Palate May Occur -
Day 34-36
Face Plates Forming -
Week 6
Muscles Form, Bent Neck, Webbed Hands and Feet, and Segmented Back -
Week 7
Fingers and Toes Separate and Eyes and Ears are Formed -
Fetal Stage Begins
Occurs when all organs are developed on day 49. -
Day 50
Genitalia Begins to Differentiate, Eyelids Fuse, and Amnion Surrounds Fetus -
Week 9-11
Chorionic Villi Sampling Could be Performed -
Week 14-15
Amniocentesis Could be Performed -
Month 6-7
Eyes Open, Fat Added Under Skin, and Head Out of Proportion to the Body
