Once a zygote is formed, the cells begin to divide ( Cleavage ) until they form a hollow ball of cells ( Blastula ). This structure then begins to fold in on itself ( Gastrulation ) to form a pore ( Blastopore ) and three distinct cell layers. Later, the formation of an additional fold ( Neurulation ) results in the neural crest (and ultimately the neural tube).
a. true
b. false
