Anatomical studies of the autonomic nervous system in the human pelvis by the whole-mount staining method: Left-right communicating nerves between bilateral pelvic plexuses

Purpose: Some recent neurophysiological studies have suggested cross-innerv ation of pelvic genitourinary organs by extrinsic left-right communicating nerves. However, no definite course for these nerves has been clearly deter mined macroanatomically in humans. In the present study we extensively inve stigated the adult human pelvis to elucidate their courses by the whole-mou nt staining method. Materials and Methods: A total of 6 male human specimens that had been subj ected to pathological dissection were examined by means of an acetylcholine sterase whole-mount staining method. A map of nerve pathways was made by co mposite photomicrography. Histologically, nerves dissected accurately under a dissecting microscope were stained with both Kluver-Barrera stain and th e Bodian method. Results: The communicating nerves between bilateral pelvic plexuses were ob served at the back of the rectum and in the rectoprostatic space. The forme r were composed of nothing but myelinated fibers in the same way as the pel vic splanchnic nerve. By contrast, the latter were composed of unmyelinated fibers with a few myelinated fibers. The pelvic plexus could be divided in to three portions, anterosuperior, anteroposterior and inferior areas, by g anglion type. Morphologically, fiber components differed among those three portions. Conclusion: The communicating nerves at the back of the rectum seemed to be predominantly parasympathetic communicantes between bilateral pelvic splan chnic nerves rather than pelvic plexuses. These nerves may be involved in p ostoperative voiding function in the case of pelvic surgery with hemilatera l nerve preservation. The function of the pelvic plexus seemed to be hetero geneous in each portion according to our morphological results.