What is released by the terminal end fibers of an axon to communicate signals between neurons?

The terminal end fibers of an axon release neurotransmitters to facilitate communication between neurons. Neurotransmitters are specialized chemicals that transmit signals across the synaptic cleft, which is the gap between two neurons. When an electrical impulse, or action potential, reaches the end of an axon, it triggers the release of these neurotransmitters from synaptic vesicles. The neurotransmitters then bind to receptors on the postsynaptic neuron, leading to a continuation of the signal or an appropriate response.

This mechanism is fundamental to how neurons communicate within the nervous system, allowing for rapid and efficient transmission of information. Other candidates like hormones and chemical signals play roles in various biological processes but are not the primary means of direct communication between neurons. Myelin, on the other hand, is a fatty substance that insulates axons and enhances the speed of signal transmission but does not function in communication between neurons.