Amphibian development
1. What type of egg does an amphibian have? What is itspattern of cleavage?2. What is the gray crescent, and when do you see it inamphibian development? What is the normal position ofthe gray crescent with respect to the first cleavagefurrow?3. Describe the relative changes in blastomere sizes in the animal andvegetal 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? Howare its cells distinctive from those of neighboring tissues?6. Why does organogenesis begin with neurulation?