Effects of Denervation on Baroreceptor and Chemoreceptor Endings in the Aorta and Pulmonary Trunk of the Domestic Fowl (Gallus Gallus Domesticus)

Denervation experiments were carried out on twelve adult domestic fowls in order to investigate the location of the cell bodies of baroreceptor and chemoreceptor endings of the aorta and pulmonary trunk. Soon after both distal vagal ganglionectomy and midcervical vagotomy, baroreceptor and chemoreceptor endings showed distinct signs of abnormalities. These abnormal signs included many irregular and deformed clear vesicles, large membranous whorls and vacuolated mitochondria. The endings which were severely affected became greatly swollen and almost empty except for a flocculent substance and disordered filamentous material. It is suggested that the cell bodies of the majority of baroreceptor and chemoreceptor endings are not in the distal vagal ganglion and may be in the proximal vagal ganglion and/or proximal or distal glossopharyngeal ganglia. The chief cells of the aortico-pulmonary bodies were also affected after denervation when their axonal endings degenerated. The degenerative changes took the form of many expanded membrane-bound empty spaces and increased size and number of the dense-cored vesicles. It is concluded that the axonal endings exert a trophic effect upon the granular cells.