-
fertilized egg
Begins to exist when the sperm enters the egg -
12 hours
pronuclei join together -
12 hours
fertilization -
zygote stage begins
begins when the egg has been fertilized and is on its way to the uterus -
30-36 hours
first round of mitosis (cleavage) -
40 hours
second round of mitosis -
50-60 hours
third round of mitosis -
50-60 hours
ectopic pregnancy -
day 4
64 cell embryo called a blastocyst -
hatching
-
8-10 days
implantation -
embryonic stage begins
begins after implantation -
day 12
disc with streak on the underside forms mesoderm -
day 12
HCG begins to be secreted -
day 15
first missed period -
day 21
heart begins to beat, arm and leg buds appear, yolk sac makes RBC's -
4th week
neural tube forms -
day 34, 35, 36
face plates forming -
5-9 weeks
cleft lip or palate may occur -
6th week
muscles form, bent neck, webbed hands and feet, segmented back -
7th week
fingers and toes separate, eyes and ears formed -
day 50
genitalia begins to differentiate, eyelids fuse, amnion surrounds fetus -
fetal stage begins
is characterized by exponential growth of the baby -
9-11 weeks
chorionic villi sampling could be performed -
14-15 weeks
amniocentesis could be performed -
6-7 months
eyes open, fat added under skin, head out of proportion to the body
