Background: With respect to need for finding suitable ways for maintenance and survival of neurons after nerve injury, also inadequacy of information for effects of peripheral nerve repair on ultrastructure of sensory neurons, this study was carried out in Iran Medical Sciences University in 2004.

Materials and Methods: In this experimental study, 24 male adult Wistar rat weighing 200-250 grams were randomly assigned in three groups of axotomy, repair, and sham. In axotomy group, left sciatic nerve transected in middle thigh and did not repaired. In repair group, sciatic nerve transected in middle thigh and repaired by epineurial suture. After 8 weeks the fifth left and right (intact) dorsal root ganglion removed. For neuronal counting, after crysel violet staining, neurons were counted with scaled lens. For ultrasrtuctural study, after primary and secondary fixation, dehydration, and impregnation, ganglions embedded with araldehyde resin. After semi thin and thin sections, and dyeing, they were observed through light and transmission electron microscopes.

Results : Average of neurons in axotomy group was 27.42±7.7 and in repair group was 33.42±11.4 (P<0.03). Semi thin sections in intact and sham groups had normal appearance. In axotomy group they showed translocation of nucleus and neucleolus, shrinkage, and pyknosis. In repair group these problems decreased completely. Thin sections in intact and sham groups were normal. In axotomy group chromatin condensation, margination and pyknosis as well as abnormal and dilated mitochondria and endoplasmic reticulum were seen. Similar changes were observed in a few of neurons in repair group.