By retrograde tracing with CT-HRP, the localization of the sympathetic efferent neurons innervating pancreas of chicken was studied.

Objective: Topography oberservation of Hsiakuan point and the location of the afferent neurons and the efferent neurons to provide the morphological foundation for Hsiakuan point acupuncture research.

It goes to prove that primary sensory neurons not only serve afferent and efferent functions, but also are sensitized after persistent noxious stimulation.