DEGENERATION AND REGENERATION OF THE OLFACTORY EPITHELIUM AFTER OLFACTORY BULB ABLATION IN THE PIG: A MORPHOLOGICAL AND ELECTROPHYSIOLOGICAL STUDY

Abstract

The olfactory bulbs were removed surgically from Large White male and female pigs, 10-12 wk of age. At intervals of 3, 7, 14, 42 and 84 days after bulbectomy, the pigs were sacrificed and portions of olfactory mucosa were removed from the ethmoturbinate and septum regions of the nasal cavity; olfactory mucosa was also removed from unoperated pigs. A piece of each tissue sample was processed for light microscopy. The remaining tissue was placed in Ringer-Locke solution, saturated with O2/CO2 at room temperature, and the electrical activity of the olfactory epithelium was investigated in vitro by passing a stimulus of butyl acetate vapor over the epithelium. Slow negative potential changes (electro-olfactogram, EOG) induced by butyl acetate were recorded. During the first 2 wk after bulbectomy there was a rapid decrease in the height of the olfactory epithelium associated with the disappearance of the EOG response. By 42 and 84 days after bulbectomy, partial recovery of the height and some electrical activity of the olfactory mucosa had occurred. In some pigs, the insertion of a stainless steel lining over the cribriform plate to prevent any association of regenerating axons with forebrain tissue had no effect on the regenerative characteristics studied.