ラット舌神経の再生に関する実験的研究

Abstract

In our clinical practice, we occasionally severed nerve fibers in treating the lingual diseases or traumatic injury of the tongue. In such cases, it seems to be very interesting how the functional disturbance was recovered physiologically or pathohistologically. The rat's lingual nerve, which was cut off at the peripheral portion in the root of the tongue, was used for the experiment. The results obtained are summarized as follows. A. Physiological findings : 1. By the 18th day after the unilateral cutting of the lingual nerve, the afferent impulses were not elicited from cutting side by tactile and chemical stimulus of the tongue surface. 2. In one of two cases on 21th day after the operation, the afferent impulses in cutting side were elicited by tactile stimuli. 3. In two cases on 31th day after the operation, the afferent impulses in cutting side were elicited by tactile and chemical stimulus. 4. Among 11 cases which lapsed from 30th to the 35th day after the operation, 3 cases showed responses to both tactile and chemical stimulus, 3 cases only to tactile stimuli. 5. Both frequency and amplitude of the afferent impulses were slowly increased as time elapsed. B. Patho-histological findings : 1. The nerve fibers in the fungiform papillae showed a slight degeneration by 24 hours after the operation. 2. The degenerative process of the taste buds in the fungiform papillae continued to be seen until about the 7th day, while the nerve fibers in connective tissue and muscular layer showed a picture of degeneration, which was swelling, laceration, granular decomposition and rosary-degeneration. 3. Taste buds had completely disappeared by the 10th day and were replaced by normal cells by 14th day. 4. Regenerated nerve fibers along Schwann's cell were observed in connective tissue and muscular layer on 17th day after the operation. 5. Regeneration of taste buds was observed in one case on 23th day after the operation. 6. The number of regenerated nerve fibers and taste buds increased as time elapsed. C. Relation between physilogical and patho-histological findings : 1. Patho-histologically, regenerated nerve fibers in connective tissue and muscular layer were observed on 17th day after the operation, while the afferent impulses were elicited on 21th day by tactile stimuli. 2. Regenerated taste buds in the fungiform papillae were observed on 23th day after the operation, while the afferent impulses were elicited on 31th day by tactile and chemical stimulus. 3. In unilateral cutting of the lingual nerve, functional recovery was obtained after morphological one, which was indicative for this experiment that the taste regained a partial recovery functionally and morphologically.