Preganglionic parasympathetic vagal innervation of the pylorus: a HRP study in the ferret (Mustela putorius furo)

The Brainstem origins of vagal preganglionic parasympathetic neurons innervating the pylorus was studied in the ferret using the Horseradish peroxidase (HRP) neurohistochemical technique. A total of 12 adult male and female ferrets (8 experimental and 4 controls) were used for the study.In each experimental ferret the pyloric canal and antrum were injected with 0.1 ml of 30% HRP in normal saline. The control ferrets were injected in a similar manner as the experimental ferret with normal saline. After 48-72 hours of post-injection survival, each ferret was perfused transcardially first with normal saline followed by a fixative containing 1 % paraformaldehyde and 1.25% glutaraldehyde in O.IM phosphate buffer, pH 7.4 at room temperature and finally with 10% buffered sucrose at 4°C. Craniotomy was performed and the brainstem excised from the brain and spinal cord. Transverse serial frozen sections of the brainstem were taken and processed for HRP neurohistochemistry and were analyzed under light and dark-field microscopy.The results of the study showed that in the experimental ferrets, neurons of the Dorsal motor nucleus of the vagus nerve (DMNV) as well as those of the nucleus ambiguous (nA) were labelled with HRP. The control ferrets did not reveal any HRP labelled neurons.