Biomedical Research

Dorsal root ganglion (DRG) contains primary sensory neurons which are said to be het-erogeneous with respect to their morphological, functional and neurochemical character-istics. Literature regarding their light microscopic features for their categorization in dif-ferent subsets remains inconclusive. The present study was attempted to see as to what ex-tent neuronal subsets of DRG can be appreciated by routine histological techniques and if there still exist some neurons with atypical features. In the present study 5 rabbits of ei-ther sex were perfusion fixed either by 10% formalin or Karnovsky’s fixative. Cervical DRGs from both sides were procured and processed for paraffin embedding. 10 μm-thick sections stained with Haematoxylin and Eosin were observed under light microscope. It was noticed that DRG neurons are arranged in groups interspersed among the fascicles of nerve fibres. They appear round or oval in shape, ranging in sizes from 15 to 75 μm in cross section, and each being surrounded by 3 to 15 satellite glial cells (SGCs). Sensory neuron is characterized by large centrally placed euchromatic nucleus and prominent nu-cleolus (1 to 3 nucleoli per neuron). Features of most of the neurons matched with those of typical neuronal subsets described by different workers (1, 2, 3, and 4). However, a very small population of neurons presented atypical features e. g; a) large cell body with coarse Nissl granules forming a prominent perinuclear ring; b) large neuron with a pyramidal or triangular somatic outline (90/50 μm); c) neuron having eccentrically placed nucleus; d) a couple of neurons sharing common SGC-sheath. It was concluded that even by routine histological techniques in addition to typical neuronal subsets some neurons having atypi-cal features can also be recognized which require appropriate categorization in accor-dance with their ultrastructural, neurochemical and functional characteristics.

Author(s): Aijaz A Khan, M Naushad A. Dilkash, M. Asim Khan* and Nafis A. Faruqi
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