Morphological heterogeneity in the cervical dorsal root ganglion neurons of mice

The dorsal root ganglion (DRG) neurons are said to be heterogeneous with respect to their morphology, function and neurochemistry. Light microscopic features for their categorization into different subsets remain inconclusive. The present study was attempted to outline certain important features of heterogeneity in cervical DRG neurons of mice. Five adult mice of either sex were perfusion fixed with 10% buffered formalin. Cervical DRGs from both sides were procured and processed for paraffin embedding. Observations were recorded from 10 µm-thick sections stained with Haematoxylin and Eosin. DRG neurons in general were arranged in clusters interspersed among the nerve fascicles. Most of them were round or oval in shape, ranging in sizes from 8 to 25 µm in cross section, had large centrally placed euchromatic nucleus and prominent central nucleolus. Each neuron was surrounded by 2 to 5 satellite glial cells. Some interesting observations included a) frequent (∼ 30%) occurrence of binucleolate neurons; b) coarse Nissl granules forming a prominent peripheral ring and c) eccentric nucleus with central or eccentric nucleoli. It was concluded that mice cervical DRG neurons possessing the afore-said interesting features required appropriate categorization in concurrence with their ultrastructural, neurochemical and functional characteristics.