BIO 529 S04
Exam III
Name______________________
ID #_______________________
1. Fill in the blanks with the best answer from the list provided. (1 pt each)
telolecithal
enveloping layer
notochord
marginal zone
node
blastocoel
trophoblast
Hox genes
neural crest
anencephaly
telencephalon
metencephalon
dendrite
spinous layer
cornified layer
neurotrophin
limb bud
ephrin
shield
organizer
node
Spina bifida
dendrite
chordamesoderm
Inner cell mass
isolecithal
epiblast
Nieuwkoop center
area pellucida
primitive streak
chordamesoderm
compaction
neural plate
neural groove
spina bifida
diencephalon
myelencephalon
axon
basal layer
Malpighian layer
autopod
limb field
netrin
mesolecithal
hypoblast
organizer
area opaca
primitive groove
chorion
allantois
neural tube
neural folds
neuropore
yolk sac
glia
growth cone
keratin
melanocyte
stylopod
progress zone
semaphorin
yolk syncytial layer
shield
paraxial mesoderm
lateral plate mesoderm
intermediate mesoderm
inner cell mass
anterior visceral endoderm
oligodendrocyte
primary neurulation
secondary neurulation
mesencephalon
intermediate zone
ventricular zone
granular layer
Schwann
zeugopod
apical ectodermal ridge
zone of polarizing activity
Three names from three different animals that all refer to the
structure that establishes dorsal-ventral polarity.
Defect resulting from failure of neural tube closure in the posterior.
Structure through which a neuron receives a signal.
Tissue that will give rise to the notochord.
Portion of the early mammalian embryo that gives rise to the embryo,
yolk sac, allantois, and amnion.
Outer layer of the epidermis.
Cornified layer
Secondary neurulation Process in which neural tube forms by the condensation of
mesenchymal cells that then hollow out.
Part of the brain associated with olfaction (smell).
telencephalon
Part of the brain associated with vision.
diencephalon
Part of the brain associated with coordination of movements.
metencephalon
Protein deposited in granules of skin cells.
keratin
Protein found in sclerotome that prevents migration of neural crest.
ephrin
Segment of vertebrate forelimb that forms the humerus.
stylopod
Segment of vertebrate forelimb that forms the hand/paw/wing.
autopod
Fate of neural crest cells that migrate between dermis & epidermis.
melanocyte
Chick or mammalian equivalent of the blastopore.
Primitive groove
All cells that are competent to contribute to the tetrapod limb.
Limb field
Cell that myelinates neurons of the peripheral nervous system
Schwann
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BIO 529 S04
Exam III
Name______________________
ID #_______________________
For all remaining questions, you must show your work or explain your reasoning to receive
any partial credit.
2. List three differences between early development in mammals as compared with other
vertebrates. Be specific. (9 pts)
3. Explain the anatomical basis for left-right asymmetry in mammals and the hypothesis for
how this may chemically/molecularly induce differences in the cells of the left and right sides
of the animal. (6 pts)
4. a. Name the two “signaling centers” involved in A/P axis determination in mammals. (4 pts)
b. From what germ layers do each of these centers derive? (3 pts)
c. What is the relationship of these centers to each other (how does one influence the other)?
(3 pts)
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BIO 529 S04
Exam III
Name______________________
ID #_______________________
5. Describe step-by-step the process of neural tube formation in primary neurulation. (8 pts)
6. For each of the following developmental processes, indicate which signaling pathways or
molecular families from the list below are critical. Note that there can be more than one
answer per process and each molecule/pathway can be used more than once. (+2 pt for each
correct, -2 pt for each incorrect; min 0/ max 16)
Molecules/pathways: -catenin/Wnt, Hedgehog, JAK/STAT, BMPs, FGFs, Receptor
Tyrosine Kinases, Hox genes
a. Proximal/distal axis formation in mammalian limb
FGF, Hox
b. Anterior/posterior axis formation in mammalian limb
Hh, Hox
c. Dorsal/ventral axis in mammalian limb
Wnt
d. Anterior/posterior axis formation in vertebrate embryo
Wnt, Hox
e. Dorsal/ventral axis formation in vertebrate embryo
-catenin/Wnt, BMP
f. Axonal guidance invertebrates
RTK
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BIO 529 S04
Exam III
Name______________________
ID #_______________________
7. For many years, experimenters examined the roles of tissue interactions in patterning the
vertebrate limb by surgically removing or transplanting those tissues in developing animals.
Based on your knowledge of those tissue interactions, predict the outcome of the following
surgical experiments in chick embryos. For each, be sure to indicate what tissue would arise,
including specific limb segments, and any altered polarities of the tissue. (15 pts)
a. The ectoderm overlying the wing limb bud is removed after production of the stylopod.
Truncation at the stylopod
b. The ectoderm overlying the wing limb bud is replaced with the ectoderm from a leg bud
after the production of the stylopod.
Normal wing
c. The mesoderm underlying the posterior of the early leg bud is transplanted to the anterior
of the wing bud after production of the stylopod.
Duplication of posterior elements st each end with anterior in the middle (mirror
image duplication) of normal wing digits
d. The ectoderm and mesoderm from the tip of a humeral stage wing bud replace the
ectoderm and mesoderm at the tip of a leg bud after production of the zygopod.
Leg stylopod & zeugopod, then wing zeugopod & autopod
e. The ectoderm tip of a wing bud after production of the zeugopod is added to the tip of a
leg bud after production of the stylopod.
Duplication of leg zeugopod & autopod
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BIO 529 S04
Exam III
Name______________________
ID #_______________________
8. In the assigned reading from Riddle et al. (Cell paper from 1993), prior to directly testing for
ability to replace the ZPA by expressing Sonic hedgehog in implanted fibroblasts, what
experimental results made the authors think that Shh could be responsible for the properties
of the ZPA? (Hint: Think about the early figures of the paper) (6 pts)
9. A researcher reports that he has discovered a new protein, Inhibin, that he believes inhibits the
migration of neural crest cells through the sclerotome. He demonstrates that Inhibin is
specifically made in the anterior of each sclerotome. Another researcher claims that this
report must be inaccurate. (10 pts)
a. Do you believe the report about Inhibin? Why or why not?
b. Propose a simple in vitro experiment (ie. not in the animal) to test whether Inhibin is an
inhibitor of neural crest cell movement. Include possible results and their interpretations.
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