The present study was carried out to investigate the retrograde reaction in the primary sensory neurons of the rat trigeminal ganglion after tooth ex­traction.
Forty adult albino rats of both sex­es with average body weight were used in this study. The animals were subjected to extraction of the lower left incisor tooth and the right non-operated side was used as control. Rats were sacrificed at survival peri­ods ²- ⁷- ^u- ²¹ and 28 days after the day of tooth extraction (8 rats for each survival period). The control and experimental trigeminal ganglia, were dissected out and processed for light microscopic examination using cresyl
violet, toluidine blue. The trigeminal ganglia of two rats were removed at ²- ⁷' and 14 days after tooth extrac­tion and were processed for electron microscopic examination.
Light microscopic examination of sections of the trigeminal ganglia re­vealed signs of degeneration in nerve cells in the form of chromatolysis and displacement of the nucleus. Signs of chromatolysis were absent in the con­trol ganglia. Staining the trigeminal ganglia for acid phosphatase activity revealed strong acid phosphatase ac­tivity in almost all the nerve cells at all the survival periods after tooth extrac­tion. The control nerve cells showed absence of acid phosphatase activity.