The percentage of nerve cell bodies arranged in clusters decreases with age in the spinal ganglia of adult rabbits.

In the spinal ganglia of the rabbit the nerve cell bodies, which in early developmental stages are mutually in contact, come to be completely isolated from each other by a satellite cell sheath and by a connective envelope before birth. The present study demonstrates that in the early postnatal months some nerve cell bodies are still arranged in clusters, and that the percentage of these decreases progressively throughout adult life. This decrease probably arises because in some of the ganglion neurons the process of envelopment of the perikaryon by an individual sheath begins later, or takes place more slowly, than in the majority of cases. Therefore, the relationship between neurons and between neurons and satellite cells may change in certain clusters of nerve cell bodies under normal circumstances during adult life.