Amphibian Development

1. What type of egg does an amphibian have? What is its
pattern of cleavage?
2. What is the gray crescent, and when do you see it in
amphibian development? What is the normal position of
the gray crescent with respect to the first cleavage
3. Describe the relative changes in blastomere sizes in the animal and
vegetal poles from the start of cleavage to the blastula stage.
4. What changes take place during gastrulation.
5. What is the notochord? When is the notochord first apparent? How
are its cells distinctive from those of neighboring tissues?
6. Why does organogenesis begin with neurulation?