Final answer:
The tip of an embryonic nerve cell's axon is called a growth cone. The neural crest is associated with the development of the peripheral nervous system, where bundles of axons are known as nerves. Growth factors direct ectodermal cells to differentiate into structures like the neural plate and neural tube.
Step-by-step explanation:
The tip of an embryonic nerve cell's axon is called a growth cone. This structure is critical in the development of the nervous system as it helps guide the growing axon towards its synaptic target by sensing the chemical and physical environment. In terms of the embryologic development of the peripheral nervous system, it is the neural crest that is primarily associated as it gives rise to a diverse set of cell types including neurons and glia of the sensory, sympathetic, and parasympathetic nervous systems. Bundles of axons in the peripheral nervous system are referred to as nerves. Growth factors play a crucial role in the differentiation of ectodermal cells into various structures. For instance, they signal some of the ectodermal cells to form epidermal cells while others form the neural plate which eventually gives rise to the neural tube, a structure that sets up the vertebrate central nervous system.