Nerves in the intersphincteric space of the human anal canal with special reference to their continuation to the enteric nerve plexus of the rectum

Abstract

In the intersphincteric space of the anal canal, nerves are thought to "change" from autonomic to somatic at the level of the squamous-columnar epithelial junction of the anal canal. To compare the nerve configuration in the intersphincteric space with the configuration in adjacent areas of the human rectum, we immunohistochemically assessed tissue samples from 12 donated cadavers, using antibodies to S100, neuronal nitric oxide synthase (nNOS), and tyrosine hydroxylase (TH). Antibody to S100 revealed a clear difference in intramuscular nerve distribution patterns between the circular and longitudinal muscle layers of the most inferior part of the rectum, with the former having a plexus-like configuration, while the latter contained short, longitudinally running nerves. Most of the intramural ganglion cells in the anal canal were restricted to above the epithelial junction, but some were located just below that level. Near or at the level of the epithelial junction, the nerves along the rectal adventitia and Auerbach's nerve plexus joined to form intersphincteric nerves, with all these nerves containing both nNOS-positive parasympathetic and TH-positive sympathetic nerve fibers. Thus, it was histologically difficult to distinguish somatic intersphincteric nerves from the autonomic Auerbach's plexus. In the intersphincteric space, the autonomic nerve elements with intrapelvic courses seemed to "borrow" a nerve pathway in the peripheral branches of the pudendal nerve. Injury to the intersphincteric nerve during surgery may result in loss of innervation in the major part of the internal anal sphincter.

Levator ani muscle innervation: Anatomical study in human fetus

“…Indeed, we already demonstrated the internal validity with a high reproducibility . Moreover, external validity of these antibodies has been also demonstrated by others teams . For PS100, Schwann cell is the preponderant cell type of peripheral nerve; hence, we considered that it labeled the vast majority of peripheral nerve fibers .…”

The Urethral Rhabdosphincter, Levator Ani Muscle, and Perineal Membrane: A Review

“…With reference to Hieda et al [18] and Hinata et al [19], the primary antibodies used for nerve immunohistochemistry were (1) mouse monoclonal anti-human S100 protein (1 : 200 dilution; Dako Z0311; Dako, Glostrup, Denmark), (2) rabbit polyclonal anti-human neuronal nitric oxide synthase (nNOS) (1 : 200; Cell Signaling Technology, Beverly, MA), (3) mouse monoclonal anti-human vasoactive intestinal peptide (H-6 or VIP) (1 : 100 dilution; Santa Cruz sc25347; Santa Cruz, CA), and (4) rabbit polyclonal anti-human tyrosine hydroxylase (TH) (1 : 100; Millipore-Chemicon ab152, Temecula, CA). With reference to Arakawa et al [20] and Abe et al [6], the antibodies used for immunostaining of fibrous structures were (1) mouse monoclonal anti-human desmin (dilution, 1 : 50; Dako) and (2) mouse monoclonal anti-human alpha smooth muscle actin (1 : 100; Dako M0851, Glostrup, Denmark).…”

“…The interface smooth muscles are also continuous with the rectourethralis muscle [38] (Figure 5(b)). Nerves supplying the internal anal sphincter originate from the periprostatic neurovascular bundle, run downward, and penetrate the rectal wall along the conjoint longitudinal muscle [18]. This kind of elastic interface between a striated muscle and a soft tissue target would seem to minimize any damage or tears resulting from sudden and strong contraction of the LA.…”

Surface Electromyography Reliably Records Electrophysiologically Evoked Internal Anal Sphincter Activity: A More Minimally Invasive Approach for Monitoring Extrinsic Innervation

“…The extrinsic nerve supply to the IAS is difficult to trace and may continue to be an imaginary feature for pelvic surgeons unless a breakthrough in surgical procedure occurs [9,10]. However, considerable immunohistochemical findings of the fascinating nature of IAS innervations [11,12] may be brought into conformity with the electrophysiological observation.…”