Ultrastructure of the gallbladder paraganglia.

The ultrastructure of the paraganglia in the gallbladder is identical to that of other nonchromaffin paraganglia featuring granule-bearing chief cells with many axons ensheathed by supporting cells. Synapses between axons, chief cells, and axons and chief cells are common. Ultrastructural similarities to the carotid body, proven to be a chemoreceptor, support a similar function for these paraganglia. An endocrine function is also suggested by the partial similarity of their structure to that of Zuckerkandl's organ.