The Central Distribution of the Vagal Efferent Neurons Projecting into the Stomach of the Japanese Field Vole (Microtus montebelli )

Abstract

Distribution pattern of the vagal preganglionic neurons in the dorsal motor nucleus of the vagus nerve (DMN) and nucleus ambiguus (NA) projecting into the stomach of the Japanese field voles (Microtus montebelli) was examined using horseradish peroxidase (HRP). The HRP was injected into ten different stomach regions covering the forestomach, glandular region and pyloric stomach. The labeled neurons in the DMN were in every injected case, while labeled neurons in the NA were in the HRP injected into the forestomach and pyloric stomach. After a separate injection of HRP into the ventral and dorsal stomachs, the labeled neurons were predominant in the left and in the right DMNs, respectively. Medio-lateral and rostro-caudal distribution of HRP-labeled neurons showed that many of them were in the medial part and near the level of the obex in the DMN. Especially innervating neurons of glandular region were remarkably restricted in the medial part and at the level of the obex in the DMN. The present investigation showed that majority of neurons supplying each stomach region were in the DMN with site specific and topographic arrangement, and a considerable number of labeled neurons were distributed symmetrically in the NA.