Study of behavioral and histological change in mice following olfactory bulbectomy.

Behavioral and histological changes in mice following bilateral olfactory bulbectomy were studied. Mice were trained to discriminate between a 0.01% Cycloheximide solution and distilled water. After olfactory bulbs were removed, discrimination was lost, and had not returned 300 days after bulbectomy. The histological changes observed by light microscope were as follow. Degeneration of olfactory epithelium was observed immediately after the bulbectomy, followed by decrement of the epithelial thickness and the number of olfactory cells. An increase in both epithelial thickness and the number of olfactory cells was observed 14 days after the bulbectomy, and epithelial thickness 300 days after the bulbectomy was similar to that of the sham-operation group. At 300 days after the bulbectomy, axons of olfactory cells migrated through the lamina cribrosa, but didn't contact the forebrain. In this study, the olfactory bulb was considered to have played a role in functional recovery of olfactory behavior, and that olfactory cells were continuously renewed under conditions of target organ, i.e. olfactory bulb, loss.