Neural interrelationships of autonomic ganglia from the pelvic region of male rats.

Abstract The aims of the present study were to describe, in male rats, the anatomical organization of the major and accessory pelvic ganglia (MPG, AG; respectively), the interrelationship of the pelvic plexus components, and the morphometry of the pelvic postganglionic neurons. Anatomical, histochemical and histological studies were performed in anesthetized adult Wistar male rats. We found that the pelvic plexus consists of intricate neural circuits composed of two MPG, and three pairs of AG (AGI, AGII, AGIII) anatomically interrelated through ipsilateral and contralateral commissural nerves. Around 30 nerves emerge from each MPG and 17 from AGI and AGII. The MPG efferent nerves spread out preganglionic information to several pelvic organs controlling urinary, bowel, reproductive and sexual functions, while AG innervation is more regional, and it is confined to reproductive organs located in the rostral region of the urogenital tract. Both MPG and AG contain nerve fascicles, blood vessels, small intensely fluorescent cells, satellite cells and oval neuronal somata with one to three nucleoli. The soma area of AG neurons is larger than those of MPG neurons (p < 0.005). The MPG contains about 75% of the total pelvic postganglionic neurons. Our findings corroborated previous reports about MPG inputs, and add new information regarding pelvic ganglia efferent branches, AG neurons (number and morphometry), and neural interrelationship between the pelvic plexus components. This information will be useful in designing future studies about the role of pelvic innervation in the physiology and pathophysiology of pelvic functions. Graphical abstract The pelvic plexus in the male rat is composed by 4 bilateral ganglia (major pelvic ganglia, MPG and three accessory ganglia, G I, II and III), two input nerves, ipsilateral and contralateral commissural nerves and efferent nerves. IMG, inferior mesenteric ganglion; HG, hypogastric nerve; PN, pelvic nerve; PD, pudendal nerve; SBPd, sensory branch of the pudendal nerve, DNP, dorsal nerve of the penis, CN, cavernous nerve. Dots represent soma neurons within the pelvic plexus. Unlabelled Image Highlights • The pelvic plexus of the male rat is made of two major ganglia and three pairs of accessory ganglia. • The components of the pelvic plexus are anatomically interrelated through ipsilateral and contralateral commissural nerves. • The accessory ganglia represent around 25% of the postganglionic pelvic innervation. • Efferent nerves of the MPG present a topographical organization. [ABSTRACT FROM AUTHOR]