Ultrastructural changes in nervous elements associated with the granular cells of the common carotid artery of the domestic fowl after distal vagal ganglionectomy.

Intramural granular cells of the left and right common carotid artery of the domestic fowl were examined with the electron microscope after left distal vagal ganglionectomy. The vast majority of the nerve fibers and endings associated with the granular cells of the left common carotid artery degenerated rapidly after ipsilateral ganglionectomy, indicating that they are derived from the left vagus. On the other hand, left distal vagal ganglionectomy resulted in transformation of the intramural granular cells of the right common carotid artery and the few nervous elements associated with them, into a typical chemoreceptor tissue. This tissue was made up of small granule (60-120 nm) containing cells associated with many nerve fibers, nerve endings and fenestrated capillaries. The nerve endings were of two types; presumptive afferent endings and adrenergic efferent endings. Both types of endings made synaptic junctions with the granular cells.