Tissue Transplants Reveal the Process of Determination
1.
Draw the amphibian egg. Label and define the animal pole and the vegetal pole.
2.
Where does the sperm enter the amphibian egg?
3. What happens opposite to the site of sperm entry? Draw a picture of the result and label.
4.
What happens if you split the zygote in half so that each half gets part of the grey crescent?
5.
What happens if you split the zygote and one side does not get any of the grey crescent?
6. What do the cells in the grey crescent give rise to?
7.
What is gastrulation?
TRANSPLANTATION
8.
During EARLY gastrulation, what happens if neural tissue is inserted into ectoderm tissue
destined to become skin?
9.
Is the fate of early gastrula cells determined yet?
10. During LATE gastrulation, what happens if neural tissue is inserted into ectoderm tissue destined
to become skin?
11. Sometime during gastrulation what happens to the fate of the cells?
12. Genetic transplantation experiments support the link between gene expression and normal
development. Explain how this experiment links to gene expression. (This answer is not in the
video. It is in your brain as you have already been learning this for a while now.)
EMBRYONIC INDUCTION
13. In frogs, some cells in the grey crescent fold inward to form the _______________lip.
14. What happened when the scientists transplanted the dorsal lip from one gastrula to another?
15. Why did the scientists name the dorsal lip the primary embryonic organizer?
16. Embryonic induction in development results in the correct timing of events. Explain this
statement.