-
Start
Fertilization -
Fertilized Egg
Begins when a sperm penetrates the ovum. -
Zygote Stage Begins
Occurs when a sperm fertilizes the ovum. -
Day 1 Hour 12
Pronuclei Join Together -
Day 2 Hour 9
First Round of Mitosis (Cleavage) -
Day 2 Hour 16
Second Round of Mitosis -
Day 3 Hour 7
Morula Formed -
Hatching
-
Day 5 Hour 1
Ectopic Pregnancy Could Occur -
Day 6 Hour 1
64 Cell Embryo Called a Blastocyst -
Day 9 Hour 1
Implantation -
Day 12 Hour 1
hCG begins to be secreted -
Day 12 Hour 2
Disc with streak on the underside forms mesoderm -
Day 15 Hour 1
First Missed Period -
Day 18 Hour 1
Neural tubes form -
Day 18 Hour 2
Heart begins to beat, arm & leg buds appear, yolk sac makes RBCs -
Day 35 Hour 1
Facial plates forming -
Embryo Stage Begins
Occurs when the organism reaches 5 weeks after gestation and continues multiplication and development of cells. -
Day 36 Hour 1
Cleft lip or palate may occur -
Week 6 Day 42 Hour 1
Muscles form, bent neck, webbed hands and feet, segmented back -
Week 7 Day 49 Hour 1
Fingers & toes separate, eyes & ears formed -
Day 50 Hour 1
Genitalia begins to differentiate, eyelids fuse, amnion surrounds fetus -
Fetal Stage Begins
Occurs when the organism reaches 8 weeks after gestation and all the organs are developed only in need of growth. -
Day 70 Hour 1
Chorionic villi sampling could be performed -
Day 100 Hour 1
Amniocentesis could be performed -
Week 26 Day 182 Hour 1
Eyes open, fat added under skin, head out of proportion to the body
