1. Embryonic Development
Department of Biology, WCU

2. Introduction Differentiation Periods of development Embryonic Fetal
Childhood
Adolescence
Adulthood
Senescence

3. Embryogenesis
1. Fertilization
zygote

4. Embryogenesis
2. Cleavage
rate of mitosis is high
morula

5. Embryogenesis
3. Blastocyst
blastocoel
trophoblast
inner cell mass

6. Implantation

7. Embryogenesis 4. Blastula trophoblast expands in size
bilaminar germ disk

8. Embryogenesis 5. Bilaminar disk amniotic space
yolk sac (gut, early RBC’s)
amnion (enclose embryo)

9. Embryogenesis 5. Gastrulation Primitive streak Primitive knot
Bilaminar to a trilaminar disk
ectoderm
endoderm
Primitive streak
Primitive knot

10. Gastrulation
Trilaminar disk
Mesoderm

11. Gastrulation 6. Trilaminar disk Bilaminar areas Stromodeum Proctodeum
oropharyngeal membrane
cloacal membrane
Stromodeum
Proctodeum

12. Differential Growth

13. Neuralation
7. Notochord
from mesoderm
vertebrates
begins nerve cord

14. Neuralation
8. Neural tube
spina bifida

15. Neurulation
9. Neural tube
neural crest cells: PNS
neural tube: CNS

16. Body folding
Umbilical cord

17. Mesoderm A. Somites Sclerotome: vertebrae, ribs
Dermatome: dermis of skin
Myotome: muscles

18. Mesoderm
B. Intermediate mesoderm
gonads, kidneys, adrenal cortex

19. Mesoderm C. Lateral plate mesoderm somatic mesoderm
splanchnic mesoderm