Embryology Timeline Flashcards
1
Q
Day 1
A
Fertilization of ovum
2
Q
Days 1-3
A
Cleavage of zygote into morula
3
Q
Day 4
A
Formation of early blastocyst
4
Q
Day 6
A
Implantation begins
5
Q
Days 14-15
A
Germ-layer formation starts (gastrulation)
6
Q
Days 17-20
A
Neurulation takes place
7
Q
Day 24
A
Embryo acquires a tadpole shape after folding of the embryonic disc
8
Q
Day 28
A
Basic human body plan is attained; limb buds are first visible
9
Q
Week 4
A
Heart begins pumping blood
10
Q
Weeks 4-8
A
body starts to become recognizably human; all major organs are formed.
11
Q
Week 8
A
First brain waves occur in brainstem
12
Q
Week 9
A
Beginning of fetal period
13
Q
Month 3
A
sex can be determined form genitals
14
Q
Month 4
A
Bones become distinct and joint cavities are apparent
15
Q
Month 5
A
Mother first feels fetus moving (“quickening”)
