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What are the Stages of Embryonic Development?
1. Name the 5 major stages of embryonic development and explain why each stage is a
significant milestone in development of animals.
2. Regarding embryonic cleavage and blastula formation:
compare the rate of cell division at these stages
indicate how yolk affects these stages in amphibians and birds
draw the blastula stage of a sea urchin, frog, and bird (label the blastocoel in
each)
draw a mammalian blastocyst and explain how in differs from the blastula of the
above animals (label the inner cell mass and trophoblast)
3. Regarding gastrulation:
describe the general process of gastrulation and indicate how it establishes the
animal body plan
compare the process of gastrulation in the sea urchin vs. birds
discuss why mammalian gastrulation occurs as in birds, even though mammalian
eggs have no yolk
explain the major change in genome expression that occurs around the time of
gastrulation; why does this change occur at an earlier stage in mammals?
4. Describe the process of neurulation and indicate the structures that develop from the
neural tube.
5. Explain the origin of neural crest cells and name a few structures that develop from
these cells.
6. Indicate the origin and location of somites in the embryo, then name two structures
that will develop from somites.
7. Name several organs and/or cell types that develop from the embryonic
ectoderm
mesoderm
endoderm
8. Name the 4 extraembryonic membranes of bird and reptile embryos and explain the
function of each (relative to embryonic development within an egg laid on land).
9. Describe how the above membranes have become adapted by mammals for
development within the uterus.
10. Be able to define the following terms:
blastopore
germ layer
primitive streak
notochord
neural fold
cell differentiation
placenta