I'm a little confused about the difference between the dorsal root ganglia and the ventral root. Im unsure about the arrangement of axons vs. cell bodies in both of these regions and where the nerves go after they exit here.
Spinal (also called dorsal root) ganglia initially appear as aggregations of neurons (nerve cell bodies) dorsolateral to the spinal cord during development. These neurons are interesting because they have processes that go back toward the spinal cord (central processes) and other processes that travel away from the ganglia and go out to receptors in the periphery (peripheral processes). Central processes of the dorsal root ganglionic neurons enter the spinal cord and synapse on neurons (nerve cell bodies) in the dorsal horn of the spinal cord. As these central processes enter the spinal cord they form the dorsal roots. Peripheral processes of these same spinal ganglionic cells pass away from their ganglia of origin and contribute to the formation of spinal nerves. Each spinal nerve has a spinal ganglion associated with it with the possible exceptions of the first cervical nerve and the coccygeal nerve. The ventral roots begin from cell bodies inside the spinal cord, that is, from ventral horn neurons of the spinal cord. These ventral horn neurons give rise to fibers that exit the spinal cord and join with the dorsal roots near the spinal ganglia to form a typical spinal nerve. The human spinal cord can be divided into 31 sections or segments and each segment gives rise to a spinal nerve and each nerve has contributions to it from dorsal and ventral roots. The spinal nerves are distributed throughout the body taking impulses to muscle and glands causing them to contract or secrete or bringing sensory impulses back to the spinal cord for pain, temperature, and touch. I have attached a picture for you that may be helpful. I borrowed the picture from a Dr. Eric Chudler at the University of Washington who maintains a "Neuroscience for Kids" website at http://faculty.washington.edu/chudler/neurok.html Don't let that name fool you as this site has a great deal of information about the brain for teachers and students. If you go to the home page listed above, you will see a link entitled "Explore the Nervous System" and on that page you will find links to information on the spinal cord. I highly recommend you take a look at this excellent resource.