-
Fertilization occurs
-
Fertilized egg
Occurs with fertilization and is known as such for the first 12 hours -
Pronuclei join together (12 hours)
-
Hour 12
Zygote stage begins -
30 hours
First round of mitosis {cleavage} -
40 hours
Second round of mitosis -
Morula formed
-
Embryonic stage begins
begins when the third cleavage occurs and forms a morula -
50 hours
Third round of mitosis -
144 hours (day 6)
64 cell embryo called blastocyte. -
192 hours (day 8)
Implantation occurs -
240 hours (day 10)
Ectopic pregnancy could occur. -
10 days
Hatching -
288 hours (day 12)
Disc with streak on underside forms mesoderm. -
288 hours (day 12)
bCG begins to secrete -
360 hours (day 15)
First missed period -
67 hours (day 18)
neural tubes form -
139 hours (day 21)
Heart begins to beat, arm and leg buds appear, yolk sac makes RBCs -
86 hours (day 34)
face plates begin to form. -
Week 6
muscles form, bent neck, webbed hands and feet, segmented back -
Week 7
Fingers and toes separate, eyes and ears formed -
Day 50
Genitalia begins to differentiate, eyelids fuse, amnion surrounds fetus -
Week 9
Chorionic villi sampling could be performed -
Fetus stage begins
Occurs when all organs are formed -
Week 14
Amniocentesis can be performed -
6 months
Eyes open, fat added under skin, head out of proportion to the body
