Vagal projections to the pylorus in the domestic pig (Sus scrofa domestica).

The goal of the present study was to examine the precise localization of the brainstem motor and primary sensory (nodose ganglion) vagal perikarya supplying the pylorus in the domestic pig. Using the Fast Blue retrograde tracing technique it has been established that all the vagal motor neurons projecting to the pylorus (about 337 ± 59 cells per animal) were localized bilaterally in the dorsal motor nucleus of the vagus nerve (DMX, 171 - left; 167 - right) and all other regions of the porcine brainstem were devoid of labeled neurons. The vagal perikarya supplying the porcine pylorus were dispersed throughout the whole rostro-caudal extent of the DMX and no somatotopic organization of these neurons was observed. The labeled neurons occurred individually or in groups up to five cell bodies per nuclear transverse cross section area (in the middle part of the nucleus). An immunocytochemical staining procedure disclosed that all Fast Blue labeled motor neurons were choline acetyltransferase (ChAT) immunoreactive, however some differences in immunofluorescence intensity occurred. The primary sensory vagal neurons were observed within the left (215±37 cells/animal) and right (148±21 cells/animal) nodose ganglion. The traced neurons were dispersed throughout the ganglia and no characteristic arrangement of these neurons was observed. The present experiment precisely indicates the sources of origin of the vagal motor and primary sensory neurons supplying the pyloric region in the pig, the animal of an increasing significance in biomedical research.