An axonal growth cone has reached a muscle fiber and is forming a neuromuscular junction. Which of the following events does NOT normally occur in this process?
A) Agrin secreted from the growth cone serves as a signaling molecule affecting the muscle cell.
B) LRP4 on the surface of the growth cone serves as a signaling molecule affecting the muscle cell.
C) Synaptic vesicles containing the neurotransmitter acetylcholine appear in the growth cone.
D) Acetylcholine receptors cluster on the muscle cell plasma membrane at the junction.
E) A thin layer of basal lamina forms at the cleft between the two cell membranes at the junction.

Question

Quizplus · Accepted Answer

Signaling occurs in both directions for the formation of a neuromuscular junction. Agrin is released from the growth cone and binds to its receptor, LRP4, on the surface of the muscle cell. In addition to its role as a co-receptor, LRP4 also serves as a signaling molecule to stimulate the formation of presynaptic structures in the neuron.

An Axonal Growth Cone Has Reached a Muscle Fiber and Is