Support and satellite cells within the rabbit dorsal root ganglion: Ultrastructure of a perineuronal support cell

STUDY DESIGN. The membrane, nucleus, and cytoplasmic contents of satellite cells were evaluated using a transmission electron microscope. OBJECTIVE. To delineate satellite cell morphometries. SUMMARY OF BACKGROUND DATA. The role of the satellite support cells associated with the neuronal cell bodies remains poorly understood. Previous research has identified one type of satellite support cells. METHODS. Dorsal root ganglions were excised from 10 adult New Zealand White rabbits. Sections from L2-L5 ganglions were prepared, cut, and analyzed under a transmission electron microscope. RESULTS. A total of 190 neurons and their associated satellite cells were selected for analysis. Three subgroups of satellite cells were identified. The two predominant subgroups consisted of previously described satellite cells. The third subgroup consisted of highly complex and unusual cells. Nineteen satellite cells (4%) did not conform to any previous description of glial cells. Cells were characterized by larger nuclei, with numerous inclusions, and by extensively convoluted reflections of the cellular membrane. These cells were "perched" or "piggy-backed" on top of a convoluted and multilayered cytoplasmic sheet. CONCLUSION. A new type of support cell representing a different cell line or a highly adapted cell with specific functional capacities was identified.