ラット舌下神経核における舌筋支配運動神経細胞の局在

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The topography of the hypoglossal (XII) motoneurons with respect to tongue muscles in the rat was studied using horseradish peroxidase (HRP). The motoneurons in the XII nucleus innervating the tongue muscles were retrogradely labeled following injection of HRP into the tongue. The injection site of HRP involved either the entire tongue or parts of the tongue. In the latter case, HRP was locally injected into anterior, intermediate, or posterior parts of the tongue. The TMB method was used for the histochemical demonstration of HRP. The XII nucleus was divided into two divisions, the dorsal and ventral. The results were as follows ; 1. HRP-labeled motoneurons were found in the bilateral XII nuclei after injection of HRP into the entire tongue. 2. When the left XII nerve was cut and HRP was injected into the entire tongue a week after, labeled motoneurons were found only in the right XII nucleus. This indicates the ipsilateral innervation by the XII motoneurons of the tongue muscles. 3. To test localization of the XII motoneurons supplying the medial and lateral branches, one of them was alternatively severed and HRP was injected into the right side of the tongue a week after. The result showed that the medial branch arose from the ventral division of the XII nucleus, whereas the lateral branch originated from the dorsal division. It was found that the motoneurons supplying the medial branch of the XII nerve were more numerous than the motoneurons supplying the lateral branch. This supports that the medial branch of the XII nerve takes more important part in tongue movement than the lateral branch. 4. Local injection of HRP into the tongue was done to study topographical arrangement of the XII motoneurons. The motoneurons innervating the anterior, intermediate and posterior parts of the tongue were mainly distributed at the medial, central and lateral parts, respectively, in the XII nucleus. 5. Local injection of HRP into the tongue was done after severance of either the medial or the lateral branch of the XII nerve. The motoneurons supplying the medial and the lateral branches and innervating the anterior parts of the tongue through the branches were distributed in the caudal and rostral XII nucleus, respectively. On the other hand, the motoneurons supplying the medial and the lateral branches and innervating the intermediate and posterior parts of the tongue through the branches were intermingled within the rostral division of the XII nucleus. The results may reflect that the anterior parts of the tongue plays an important role in delicate movement of the tongue, compared to the intermediate and posterior parts.
九州歯科学会の論文
1995-02-25

ラット舌下神経核における舌筋支配運動神経細胞の局在

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