Download Embryonic Development

Embryonic Development Minimal Requirements for Lab
Identify Structure and Name Function
I. Models
A. Development from a zygote to a gastrula
1. Fertilization – fusion of pronuclei to form a zygote
2. Cleavage – formation of blastomeres (2-, 4-, 8- and 16-cell stages)
3. Morula
4. Blastula
i. Inner cell mass (ICM)
ii. Blastocoele (blastocyst cavity)
iii. Trophoblast
5. Gastrulation – formation of the trilaminar disk (3 primary germ layers) from
the bilaminar disk (hypoblast and epiblast)
i. Endoderm
ii. Mesoderm
iii. Ectoderm
B. Embryo – 0 to 8 weeks
C. Fetus – 9 weeks to birth
D. Implantation
1. Fetal portion – chorion that develops from the trophoblast
i. Cellular trophoblast (cytotrophoblast)
ii. Synctial trophoblast (syncytiotrophoblast)
1) Chorionic villi – containing embryonic blood vessels
E. Extraembryonic membranes
1. Yolk sac
2. Amniotic sac
3. Allantois – within the body stalk
4. Chorion
F. Umbilical cord – containing 2 umbilical arteries and 1 umbilical vein
G. Placentation
1. Maternal portion
i. Decidua basalis – maternal portion of the placenta and part of
endometrium
1) Intervillus space (lacunae) – containing maternal blood
ii. Decidua capsularis – endometrium surrounding embryo but not part of
placenta
iii. Decidua parietalis – endometrium not surrounding embryo or placenta
2. Extraembryonic coelom