Innervation of rat abdominal paraganglia by calretinin-like immunoreactive nerve fibers.

The extended hepatic pedicle of the rat containing the vagal hepatic branch and associated paraganglia was dissected as whole mount, processed for calretinin immunocytochemistry, and analyzed by laser-scanning confocal microscopy. About half of the 8-12 paraganglia of the region were innervated to a various degree by calretinin-immunoreactive (CAL-IR) nerve fibers that formed basket-like varicose terminals around small clusters of glomus tissue. Neither the numerous capillaries, nor the occasional non-CAL-IR neuron accompanying some paraganglia, were recipients of CAL-IR terminals. In animals with prior left cervical vagotomy the number of CAL-IR fibers was decreased but not abolished. Since about 30% of neurons in the nodose ganglia, a few neurons within the vagal hepatic branch/hepatic hilus area, and numerous neurons in the gastric myenteric plexus were CAL-IR, these neurons represent other potential sources of CAL-IR innervation of the paraganglia.