Final answer:
Sympathetic preganglionic neurons have short and myelinated fibers, while postganglionic neurons have long and unmyelinated fibers, due to differences in distance from the CNS to the effector organs.
Step-by-step explanation:
The sympathetic preganglionic and postganglionic neurons differ in terms of the length of their axons. The preganglionic neurons, which connect the central nervous system (CNS) to a ganglion, have relatively short and myelinated fibers because the sympathetic ganglia are located close to the vertebral column. In contrast, the postganglionic neurons, whose axons extend from the ganglia to the target effector, have long and unmyelinated fibers since they need to cover a greater distance to reach their target organs.
Preganglionic Neurons:
Length: The axons of sympathetic preganglionic neurons are relatively short.
Location of Cell Bodies: The cell bodies of these neurons are located in the lateral horns of the spinal cord's gray matter (specifically, in the thoracic and lumbar regions).
Postganglionic Neurons:
Length: The axons of sympathetic postganglionic neurons are relatively long.
Location of Cell Bodies: The cell bodies of these neurons are located in ganglia outside the spinal cord, typically in two paravertebral chains running along each side of the vertebral column (sympathetic chain ganglia) or in prevertebral ganglia closer to the target organs.
The short preganglionic neurons synapse with the long postganglionic neurons at ganglia. This structural arrangement is a characteristic feature of the sympathetic division of the autonomic nervous system. The short preganglionic neurons allow for a rapid and widespread activation of the sympathetic system in response to stress or danger.