Computer-assisted Anatomic Dissection Research Articles

Feasibility of a fetal anatomy 3D atlas by computer-assisted anatomic dissection

ObjectiveTo assess the feasibility of 3D modelisation of fetal anatomy by using the Computer-assisted anatomic dissection (CAAD) based on immunolabeled histologic slices and MRI slices with a specific 3D software. Study designFor pelvis and lower limbs, subjects came from legal abortion, medical pregnancy termination, or late miscarriage. Specimens were fixed in 10 % formalin, then embedded in paraffin wax and serially sectioned. The histological slices were stained using HES and Masson Trichrome. Protein S-100 and D2−40 markers were used for immuno-labelling. Serial transverse sections were digitalized and manually aligned. Fetal brain slices were obtained from in utero or post-mortem MRI. ResultsCAAD was performed on 10 fetuses: pelvis was modelised with 3 fetuses of 13, 15 and 24 W G, lower limbs with 2 fetuses of 14 and 15 W G and brain with 5 fetuses aged between 19 and 37 W G. Fetal pelvis innervation was analysed after immunolabelling and nerves appeared proportionally bigger than in adults with the same topography. Lower limbs analysis revealed that nerve development was guided by vascular development: the sciatic nerve along the big axial vein, the saphen nerve along the big saphen vein and the sural nerve along the small saphen vein. Fetal brain study allowed to describe the gyration process and the lateral ventricle development. ConclusionCAAD technique provides an accurate 3D reconstruction of fetal anatomy for lower limbs and pelvis but has to be improved for brain model since midline structures were not amendable for analysis. These results need to be confirmed with larger series of specimens at different stages of development.

Neurovascular and lymphatic vessels distribution in uterine ligaments based on a 3D reconstruction of histological study: to determine the optimal plane for nerve-sparing radical hysterectomy.

To present the distribution of neurovascular and lymphatic vessels in uterine ligaments using 3D models based on the pathological staining of serial 2D sections of postoperative specimens. Serial transverse sections of fresh uterine ligaments from a patient with stage IB1 cervical squamous cell carcinoma were studied using the computer-assisted anatomic dissection (CAAD) technique. The sections were stained with hematoxylin and eosin, Weigert elastic fibers, D2-40 and immunostainings (sheep anti-tyrosine hydroxylase and rabbit anti-vasoactive intestinal peptide). The sections were then digitalized, registered and reconstructed three-dimensionally. Then, the 3D models were analyzed and measured. The 3D models of the neurovascular and lymphatic vessels in uterine ligaments were created, depicting their precise location and distribution. The vessels were primarily located in the upper part of the ligaments model, while the pelvic autonomic nerves were primarily in the lower part; the lymphatic vessels were scattered in the uterine ligaments, without obvious regularity. CAAD is an effective anatomical method to study the precise distribution of neurovascular and lymphatic vessels in uterine ligaments. It can present detailed anatomical information about female pelvic autonomic innervation and the spatial relationship between nerves and vessels and may provide a better understanding of nerve-sparing radical hysterectomy.

Three-Dimensional Modelization of the Female Human Inferior Hypogastric Plexus: Implications for Nerve-Sparing Radical Hysterectomy

Background/Aims: This study aims to describe the autonomic nervous network of the female pelvis with a 3D model and to provide a safe plane of dissection during radical hysterectomy for cervical cancer. Methods: Pelvises of 3 human female fetuses were studied by using the computer-assisted anatomic dissection. Results: The superior hypogastric plexus (SHP) was located at the level of the aortic bifurcation in front of the sacral promontory and divided inferiorly and laterally into 2 hypogastric nerves (HN). HN ran postero-medially to the ureter and in the lateral part of the uterosacral ligament until the superior angle of the inferior hypogastric plexus (IHP). IHP extended from the anterolateral face of the rectum, laterally to the cervix and attempted to the base of the bladder. Vesical efferences merged from the crossing point of the ureter and the uterine artery and ran through the posterior layer of the vesico-uterine ligament. Conclusions: The SHP could be injured during paraaortic lymphadenectomy. Following the ureter and resecting the medial fibrous part of the uterosacral ligament may spare the HN. No dissection should be performed under the crossing point of the ureter and the uterine artery.

Three-dimensional computer-assisted dissection of pancreatic lymphatic anatomy on human fetuses: a step toward automatic image alignment.

Pancreatic cancer is the fourth cause of death by cancer worldwide. Lymph node (LN) involvement is known to be the main prognostic factor. However, lymphatic anatomy is complex and only partially characterized. The aim of the study was to study the pancreatic lymphatic system using computer-assisted anatomic dissection (CAAD) technique and also to update CAAD technique by automatizing slice alignment. We dissected three human fetuses aged from 18 to 34 WA. 5-µm serial sections of duodeno-pancreas and spleen blocks were stained (hematoxylin-eosin, hematoxylin of Mayer and Masson trichrome), scanned, aligned and modeled in three dimensions. We observed a rich, diffuse but not systematized lymphatic network in the peri-pancreatic region. There was an equal distribution of LNs between the cephalic and body-tail portions. The lymphatic vascularization appeared in continuity from the celiac trunk to the distal ends of its hepatic and splenic arterial branches parallel to the nerve ramifications of the celiac plexus. We also observed a continuity between the drainage of the pancreatic head and the para-aortic region posteriorly. In view of the wealth of peri-pancreatic LNs, the number of LNs to harvest could be increased to improve nodal staging and prognostic evaluation. Pancreatic anatomy as described does not seem to be compatible with the sentinel LN procedure in pancreatic surgery. Finally, we are now able to offer an alternative to manual alignment with a semi-automated alignment.

Levator ani muscle innervation: Anatomical study in human fetus.

To characterize the nature and function of the levator ani muscle innervation pathways and to perform a comprehensive three-dimensional reconstruction of female pelvic innervation. A computer-assisted anatomical dissection protocol was applied to seven female human fetuses, after approval from the national biomedicine agency. Specimens were serially sectioned and immunostained for overall (antibody against protein S100), somatic (antibody against peripheral myelin protein 22), adrenergic (antibody against tyrosine hydroxylase), cholinergic (antibody against vesicular acetylcholine transferase), and nitrergic (antibody against the neural isoform of nitric oxide synthase) nerve fibers. Slides were digitized for three-dimensional reconstructions using WinSurf®. Three main nerve pathways to the levator ani muscle were observed: the levator ani nerve, the pudendal nerve, and the inferior hypogastric plexus. The pudendal nerve was both somatic and autonomic, located below the levator ani muscle (infralevator pathway), supplying innervation to the inferior aspect of the levator ani muscle. The levator ani nerve was solely somatic, located above the levator ani muscle (supralevator pathway), supplying innervation to the superior aspect of the levator ani muscle. The inferior hypogastric plexus nerve fibers were solely autonomic, located in between the levator ani muscle and pelvic organs (endolevator pathway), supplying innervation to the medial portion of the levator ani muscle. Our study provides a new representation of levator ani muscle innervation with three nerve pathways, and the levator ani muscle itself as an anatomical landmark.

Computer‐Assisted Anatomical Dissection (CAAD) of the Renal Plexus to Refine Renal Denervation in the Treatment of Refractory Hypertension

ContextRadioFrequency (RF) renal denervation is an emerging treatment of refractory arterial hypertension with various possible approaches: endovascular, endourologic, laparoscopic. Results and adverse events remain controversial. Theoretical safety and efficiency of all of the approaches deserve to be addressed with special insight into the anatomy of the renal plexus and hilar structures. The objective was to describe the location and distances between nerve fibers and renal vasculature.MethodsSagittal serial sections were performed in 4 human fetuses and 10 adult bodies were dissected. In fetuses, sections were stained by Masson's trichrome, HE, and immunostained by PS100 neuronal antibody. The nature of renal plexus fibers was investigated by adrenergic (TH) and somatic (PMP22) labelings. In cadavers, the distances between nerve fibers and arteries were measured at the renal ostium, at mid‐artery, at the hilum of the kidney, and were statistically compared (one‐way repeated measures ANOVA). 3D reconstructions were performed from the digitized serial sections obtained in fetuses.ResultsThe renal plexus can be described as a guying contained in an hourglass shape centered on the renal artery. The isthmus of this hourglass corresponds to the hilum of the kidney and is a mandatory waypoint of afferent and efferent renal plexus. At this level, the nerves are at the closest location of arterial branches (11 mm at the renal ostium, 6.5 mm at mid‐artery and 2 mm at the hilum of the kidney; p<0.001). The sectorial distribution of the nerves around the renal artery is heterogeneous and fibers predominate on the superior aspect. Nerve fibers are autonomic (PMP22−) and adrenergic‐sympathetic (TH+). With an animated 3D reconstruction, it is possible to analyze the relationship between renal plexus, vasculature and urinary tract, and the potential risks of various denervation techniques.ConclusionCAAD in fetuses identified the renal hilum as the theoretical preferential site for renal denervation. To optimize endovascular denervation in future clinical studies, a compromise should be sought between the size of the RF probe and the arteries’ diameter. There is an opening to laparoscopic surgical denervation.Support or Funding InformationNone

Innervation of the Female Levator Ani Muscle and Consequences in Pelvic Floor Dysfunctions

IntroductionThe Levator Ani Muscle (LAM) and the Levator Ani Nerve (LAN) are distended and traumatized during pregnancy and vaginal delivery. Both mechanisms may sustainably impair the pelvis statics but the topography and functions of the nerve supply to the LAM remain anatomically controversial.ObjectiveTo characterize the nature and function of the LAM nerve pathways and to perform a comprehensive 3D reconstruction of the female pelvic innervation.MethodsThe Computer‐Assisted Anatomical dissection (CAAD) protocol was applied to pelvic blocks procured in 6 female human fetuses, in accordance with the National Biomedicine Agency. Specimens were serially sectioned and immunostained for: overall (S100), somatic (PMP22), adrenergic (TH), cholinergic (VaCHT) and nitrergic (nNOS) nerve fibers and for: smooth (smooth actin) and striated (myogenin) muscle fibers. Slides were digitized for 3D reconstructions on WinSurf®. A pelvic sample of an additional fetus was examined under electronic microscopy to analyze the ultrastructure of the LAM.ResultsThree main nerve pathways to the LAM were observed: the levator ani nerve (LAN), the pudendal nerve (PuN), the inferior hypogastric plexus (IHP). The PuN was both somatic and autonomic, located below the LAM (‘infralevator pathway’) and supplying innervation to the inferior aspect of the LAM. The LAN was solely somatic, located above the LAM (‘supralevator pathway’) and supplying innervation to the superior aspect of the LAM. The IHP nerve fibers were solely autonomic, located in between the LAM and the pelvic organs (‘endolevator pathway’) and supplying innervation to the medial portion of the LAM. Smooth muscle areas were identified with labelings and electronic microscopy: they 1) were located in the puboanal sling of the LAM 2) were bulging between rectum and vagina 3) were intermingled to the anococcygeal raphe 4) were innervated by the IHP and the PuN pathways.ConclusionHaving at once striated and smooth muscle fibers and being co‐innervated by the somatic and autonomic systems, the LAM represents a crucial anatomical structure involved in the pelvic floor function and its rehabilitation.Support or Funding Informationnone

Anatomical basis of the coordination between smooth and striated urethral and anal sphincters: loops of regulation between inferior hypogastric plexus and pudendal nerve. Immuno-histological study with 3D reconstruction

(1) Describe both nervous pathways to the sphincters, and highlight the anatomical support of their coordination. (2) Obtain a 3D representation of this complex innervation system. A computer-assisted anatomical dissection technique was used. Serial histological sections were cut in the pelvis of four female human foetuses (aged 19-32weeks of gestation). The sections were treated with conventional staining, and with seven different immunostainings. The sections were digitalized and, finally, a 3D representation was built from the corresponding images. Myelinated and sensory fibres were detected at the inferior hypogastric plexus (IHP) level. Our analysis showed that most of the afferent sensory fibres come from the urinary and anal sphincters through the anterior and posterior branches of the IHP respectively. A highly positive nitrergic (anti-NOS1) and sensitive (anti-CGRP) labelling was found in the external layer of the urethral sphincter. The 3D representation allowed describing the two components of the innervation system. A sensory-motor regulation loop was found for both sphincters. A 3D description of the components of both nervous pathways to the sphincters has been established. Our findings on the innervation of the sphincters tend to question the classical infra/supra levatorian muscle description. The coordinated work of the internal and external layers of the anal and urethral sphincter is probably mediated by multiple roles regulation.

Modélisation anatomique 3D du pelvis féminin par dissection anatomique assistée par ordinateur : applications et perspectives

To achieve a 3D vectorial model of a female pelvis by Computer-Assisted Anatomical Dissection and to assess educationnal and surgical applications. From the database of "visible female" of Visible Human Project(®) (VHP) of the "national library of medicine" NLM (United States), we used 739 transverse anatomical slices of 0.33mm thickness going from L4 to the trochanters. The manual segmentation of each anatomical structures was done with Winsurf(®) software version 4.3. Each anatomical element was built as a separate vectorial object. The whole colored-rendered vectorial model with realistic textures was exported in 3Dpdf format to allow a real time interactive manipulation with Acrobat(®) pro version 11 software. Each element can be handled separately at any transparency, which allows an anatomical learning by systems: skeleton, pelvic organs, urogenital system, arterial and venous vascularization. This 3D anatomical model can be used as data bank to teach of the fundamental anatomy. This 3D vectorial model, realistic and interactive constitutes an efficient educational tool for the teaching of the anatomy of the pelvis. 3D printing of the pelvis is possible with the new printers.

The visceromotor and somatic afferent nerves of the penis.

Innervation of the penis supports erectile and sensory functions. This article aims to study the efferent autonomic (visceromotor) and afferent somatic (sensory) nervous systems of the penis and to investigate how these systems relate to vascular pathways. Penises obtained from five adult cadavers were studied via computer-assisted anatomic dissection (CAAD). The number of autonomic and somatic nerve fibers was compared using the Kruskal-Wallis test. Proximally, penile innervation was mainly somatic in the extra-albugineal sector and mainly autonomic in the intracavernosal sector. Distally, both sectors were almost exclusively supplied by somatic nerve fibers, except the intrapenile vascular anastomoses that accompanied both somatic and autonomic (nitrergic) fibers. From this point, the neural immunolabeling within perivascular nerve fibers was mixed (somatic labeling and autonomic labeling). Accessory afferent, extra-albugineal pathways supplied the outer layers of the penis. There is a major change in the functional type of innervation between the proximal and distal parts of the intracavernosal sector of the penis. In addition to the pelvis and the hilum of the penis, the intrapenile neurovascular routes are the third level where the efferent autonomic (visceromotor) and the afferent somatic (sensory) penile nerve fibers are close. Intrapenile neurovascular pathways define a proximal penile segment, which guarantees erectile rigidity, and a sensory distal segment.

Three-dimensional reconstruction of the lower limb's venous system in human fetuses using the computer-assisted anatomical dissection (CAAD) technique.

The aim of the present study was to show the feasibility and describe the first results of a 3D reconstruction of the venous network of the lower limbs in human fetus using the computer-assisted anatomical dissection (CAAD) technique. We used limbs from two human fetuses, respectively, 14 and 15 weeks gestation old. Specimens were fixed in 10% formalin, embedded in paraffin wax and serially sectioned at 10 m. The histological slices were stained using HES and Masson Trichrome for soft tissues identification. Immunolabeling techniques using the Protein S-100 marker and the D2-40 marker were used to identify nerves and vessels, respectively. Stained slices were aligned manually, labeled and digitalized. The segmentation of all anatomical structures was achieved using the WinSurf(®) software after manual drawing. A 3D interactive vectorial model of the whole leg, including skin, bone, muscles, arteries, veins, and nerves was obtained. In all limbs, we observed the presence of a big axial vein traveling along the sciatic nerve. In addition, the femoral vein appeared as a small plexus. Although this is a common anatomical feature at the end of organogenesis, this feature is observed in only 9% of adults. Usually interpreted as an "anatomical variation of the femoral vein" it should be considered as a light truncular malformation. These observations bring further support to our proposed "angio-guiding nerves" hypothesis. This preliminary study shows that the CAAD technique provided an accurate 3D reconstruction of the fetal leg veins anatomy. It should bring a new insight for the understanding of the different steps of development of the human venous system.

Optimal plane for nerve sparing total mesorectal excision, immunohistological study and 3D reconstruction: an embryological study

Genito-urinary complications are frequent after rectal surgery and are often due to nerve damage. The relationship between the pelvic nerves and surgical planes are unclear. The aim of the study was to determine the relationship between the inferior hypogastric plexus and the fascia of the lateral pelvic wall and between Denonvilliers' fascia and the efferent branches of the inferior hypogastric plexus. Computer-assisted anatomical dissection was used. Serial histological sections were made from six human foetuses and a male adult. Sections were stained with haematoxylin and eosin, Masson's trichrome and immunostainings. The sections were then digitalized and reconstructed in three dimensions. The inferior hypogastric plexus was situated in a virtual space between the fascia propria of the rectum and the fascia on the upper surface of the levator ani. During the lateral dissection, the optimal surgical plane is the plane of the fascia propria of the rectum. We located Denonvilliers' fascia in three dimensions. It plays the role of a protective sheet for the neurovascular bundle. The optimal plane for nerve preservation is situated behind Denonvilliers' fascia. This study has enabled a clear visualization of the optimal planes to perform total mesorectal excision while ensuring nerve preservation. Three-dimensional visualization clearly helps to bridge the gap between histological examination and the findings of surgery.

What is the origin of the arterial vascularization of the corpora cavernosa? A computer‐assisted anatomic dissection study

The purpose of this study was to identify the microscopic arterial vascularization of the corpora cavernosa (CC) of the penis using computer-assisted anatomic dissection (CAAD), determine the contribution of the different penile arteries towards this vascularization, detail the nature of cavernospongiosum shunts, and locate the anastomoses between these different arteries. Tissue specimens were taken from five donors who donated their bodies to science. The specimens were fixed in 10% formalin and sliced into a series of five 5-μm sections at intervals of 200μm. The first section was stained with hematoxylin-eosin or Masson's trichrome and the second with anti-protein S100. The cavernous artery of the penis is not the only source of arterial vascularization of the CC. In four of the five cases studied, we found two to four perforating branches arising from the dorsal arteries of the penis that join up with the cavernous artery of the penis or that are solely responsible for the vascularization of the distal third of the penis. The bulbo-urethral and urethral arteries are situated outside of the tunica albuginea of the corpus spongiosum on their lateral and dorsal sides. The anastomoses do not occur between the cavernous artery of the penis and the corpus spongiosum but between the cavernous artery of the penis and the urethral artery on the surface of the tunica albuginea. All of these arteries are accompanied by nerve branches. The CC were found to be vascularized by both cavernous and dorsal arteries of the penis. Intrapenile vascularization is organized around four arterial axes, which are anastomosed by multiple neurovascular shunts.

Biomechanical origin of the Denonvilliers’ fascia

Since 1836 and the first description of the recto-genital fascia by Charles Denonvilliers, many anatomists have shown interest in this subject. Recently, pelvic surgeons have in turn shown similar interest, for they consider that perfect knowledge of this anatomical domain is crucial for optimal nerve conservation during surgery. Thanks to new anatomical description techniques, fascia location and relationships with pelvic nerves now appear clearer. To describe and represent Denonvilliers' fascia and its relationships in the female foetus at different stages of gestation and in three-dimensional space (3D). Computer-assisted anatomical dissection technique was used. Serial histological sections were made from four human female foetuses. Sections were treated with conventional staining, as well as with nerve and smooth muscle immunostaining. Finally, the sections were digitalized and reconstructed in 3D. Denonvilliers' fascia was clearly located and visualized in three dimensions. It was present in the female foetus, being distinct from the fascia propria of the rectum. It appeared to be composed of multiple parallel layers situated between the vagina and the rectum. From a lateral view, it had an asymmetrical "Y-shaped" aspect that seemed to play the role of a protective sheet for the neurovascular bundles. This study betters our comprehension of the Denonvilliers' fascia in the female foetus and of its connections with pelvic nerves. It also provides a better understanding of safe planes during pelvic dissection. These findings also suggest a biomechanical theory for embryological origin of the Denonvilliers' fascia.

Identification of the origin of adrenergic and cholinergic nerve fibers within the superior hypogastric plexus of the human fetus

Nerve fibers contributing to the superior hypogastric plexus (SHP) and the hypogastric nerves (HN) are currently considered to comprise an adrenergic part of the autonomic nervous system located between vertebrae (T1 and L2), with cholinergic aspects originating from the second to fourth sacral spinal segments (S2, S3 and S4). The aim of this study was to identify the origin and the nature of the nerve fibers within the SHP and the HN, especially the cholinergic fibers, using computer-assisted anatomic dissection (CAAD). Serial histological sections were performed at the level of the lumbar spine and pelvis in five human fetuses between 14 and 30weeks of gestation. Sections were treated with histological staining [hematoxylin-eosin (HE) and Masson's trichrome (TriM)] and with immunohistochemical methods to detect nerve fibers (anti-S100), adrenergic fibers (anti-TH), cholinergic fibers (anti-VAChT) and nitrergic fibers (anti-nNOS). The sections were then digitalized using a high-resolution scanner and the 3D images were reconstructed using winsurf software. These experiments revealed the coexistence of adrenergic and cholinergic fibers within the SHP and the HNs. One-third of these cholinergic fibers were nitrergic fibers [anti-VACHT (+)/anti-NOS (+)] and potentially pro-erectile, while the others were non-nitrergic [anti-VACHT (+)/anti-NOS (-)]. We found these cholinergic fibers arose from the lumbar nerve roots. This study described the nature of the SHP nerve fibers which gives a better understanding of the urinary and sexual dysfunctions after surgical injuries.

Autonomic-somatic communications in the human pelvis: computer-assisted anatomic dissection in male and female fetuses

Sphincter continence and sexual function require co-ordinated activity of autonomic and somatic neural pathways, which communicate at several levels in the human pelvis. However, classical dissection approaches are only of limited value for the determination and examination of thin nerve fibres belonging to autonomic supralevator and somatic infralevator pathways. In this study, we aimed to identify the location and nature of communications between these two pathways by combining specific neuronal immunohistochemical staining and three-dimensional reconstruction imaging. We studied 14 normal human fetal pelvic specimens (seven male and seven female, 15-31 weeks' gestation) by three-dimensional computer-assisted anatomic dissection (CAAD) with neural, nitrergic and myelin sheath markers. We determined the precise location and distribution of both the supra- and infralevator neural pathways, for which we provide a three-dimensional presentation. We found that the two pathways crossed each other distally in an X-shaped area in two spatial planes. They yielded dual innervation to five targets: the anal sphincter, levator ani muscles, urethral sphincter, corpus spongiosum and perineal muscles, and corpora cavernosa. The two pathways communicated at three levels: proximal supralevator, intermediary intralevator and distal infralevator. The dorsal penis/clitoris nerve (DN) had segmental nitrergic activity. The proximal DN was nNOS-negative, whereas the distal DN was nNOS-positive. Distal communication was found to involve interaction of the autonomic nitrergic cavernous nerves with somatic nitrergic branches of the DN, with nitrergic activity carried in the distal part of the nerve. In conclusion, the pelvic structures responsible for sphincter continence and sexual function receive dual innervation from the autonomic supralevator and the somatic infralevator pathways. These two pathways displayed proximal, intermediate and distal communication. The distal communication between the CN and branches of the DN extended nitrergic activity to the distal part of the cavernous bodies in fetuses of both sexes. These structures are important for erectile function, and care should therefore be taken to conserve this communication during reconstructive surgery.

Computer-assisted anatomic dissection (CAAD): evolution, methodology and application in intra-pelvic innervation study

Classic anatomical methods have limitations in micro determination of nerve fibre location. Furthermore, the precise detection of the nerve fibres nature is not possible by means of dissection. The combination of immunohistochemistry and three-dimensional reconstruction could be used to resolve these limitations of morphological sciences. Our aim is to describe the evolution of computer-assisted anatomic dissection (CAAD), which is an original method applied to study the distribution of intra-pelvic nerves in anatomic research. Serial transverse sectioning of the pelvic region in rabbit, human fetus, infant and adult cadaver was performed. Sections were immuno-histochemically stained and digitized with a high optical resolution scanner. Photoshop 7 software was used in regrouping of the adult cadaver sections then a tri-dimensional reconstruction was achieved using WinSurf software. The 3D reconstruction of the immuno-histochemically stained histologic sections of the pelvis allowed for precise structural identification of the prostate and its innervations (in fetus, infant and adult). In addition, we reconstructed the entire intra-pelvic organs with accurate demonstration of the location of both adrenergic and cholinergic pathways. Moreover, we performed a virtual dissection of each of the pelvic structures with description of the exact location of the inferior hypogastric plexus, as well as the nature and the distribution of its fibres. The CAAD is an original method in anatomic research, which illustrates the fact that descriptive anatomy is still a dynamic science. This method allows for a 3D presentation of the intra-organic innervation, the nature of the nerve fibres, and the distribution of receptors and their neurotransmitters. This technique improves the understanding of the complex anatomic regions such as the pelvis from both surgical and educational point of view.

Neural Supply to the Clitoris: Immunohistochemical Study with Three‐Dimensional Reconstruction of Cavernous Nerve, Spongious Nerve, and Dorsal Clitoris Nerve in Human Fetus

Little detailed information is available concerning autonomic and somatic nerve supply to the clitoris, potentially causing difficulties for nerve preservation during pelvic and perineal surgery. To identify the location and type (nitrergic, adrenergic, cholinergic and sensory) of nerve fibers in the clitoris and to provide a three-dimensional (3D) representation of their structural relationship in the human female fetus. Serial transverse sections were obtained from five human female fetuses (18-31 weeks of gestation) and subjected to histological and immunohistochemical investigations; digitized serial sections were used to construct a 3D representation of the pelvis. Pelvic-perineal nerve location and type were evaluated qualitatively. The female neurovascular bundle (NVB) is the anteroinferior terminal portion of the inferior hypogastric plexus that runs along the postero-lateral then lateral face of the vagina and is rich in nNOS-positive fibers. The cavernous nerve (CN) is a thin ventrocaudal collateral projection of the NVB, and this projection does not strictly follow the NVB course. The CN runs along the lateral surface of the vagina and urethra and penetrates the homolateral clitoral crus. The CN provides adrenergic, cholinergic, and nitrergic innervation to the clitoris, but not sensory innervation. The spongious nerve (SN) is the terminal and main projection of the NVB and provides nitrergic innervation to the vestibular bulbs. The dorsal clitoris nerve (DCN), somatic branche of the pudendal nerve, runs along the superior surface of the clitoral crus and body and has a segmental proerectile nitrergic activity related to communicating branches with the CN. "Computer-assisted anatomic dissection" allowed the identification of the precise location and distribution of the autonomic and somatic neural supply to female erectile bodies, providing an anatomical basis for nerve-sparing surgical techniques, and participating to the understanding of neurogenic female sexual dysfunction.

Supra and infralevator autonomic‐somatic communications: Computer‐assisted anatomic dissection in male and female foetuses

Objectiveto identify the location and the nature of communications between supra and infralevator pathways.Materials and Methods6 male and 6 female human fetal pelvic specimens, 15 to 32 wk of gestation, were studied using the 3D computer‐assisted anatomic dissection (CAAD) with neural, nitrergic and myelin sheath markers.ResultsSupra and infra levator neural pathways cross each other distally in spatial X shape area. They yield dual innervation in 5 directions: 1‐anal sphincter, 2‐levator ani muscle, 3‐urethral sphincter, 4‐corpus spongiosum and perineal muscles, and 5‐corpora cavernosa. The communications between the two pathways exist in 3 levels: proximal supralevator, intermediary intralevator and distal infralevator. Distal communications exist when autonomic nitrergic cavernous nerves interact with some somatic nitrergic branches of the dorsal penis/clitoris nerve and carried the nitrergic activity in its distal portion.ConclusionsThe pelvic structures responsible for sphincters continence and sexual function receive a dual innervation from the autonomic supralevator and the somatic infralevator pathways. Distal communication takes over the nitrergic activity to the distal part of cavernous bodies in both gender and represents an important structure which may impact erectile function, especially during reconstructive surgery.Grant Funding Source: non

Division of Autonomic Nerves Within the Neurovascular Bundles Distally into Corpora Cavernosa and Corpus Spongiosum Components: Immunohistochemical Confirmation with Three-Dimensional Reconstruction

BackgroundDetailed knowledge of the distribution and distal course of periprostatic nerves is essential to improve functional outcomes (erection and continence) after radical prostatectomy (RP). ObjectiveTo describe the location of nerve fibres within neurovascular bundles (NVBs) and around the prostate by three-dimensional (3D) computer-assisted anatomic dissection (CAAD) in human foetuses and adult cadavers. Design, setting, and participantsSerial transverse sections of the pelvic portion were performed in seven human male foetuses and four male adult cadavers. Sections were treated by histologic coloration and neuronal immunolabelling of S100 protein. 3D pelvic reconstruction was achieved with digitised serial sections and WinSurf software. MeasurementsWe evaluated the distribution of nerve fibres within the NVB qualitatively. The distribution of periprostatic nerves was also evaluated quantitatively in the adult specimens. Results and limitationsPeriprostatic nerve fibres were dispersed around the prostate on all sides with a significant percentage of these fibres present in the anterior and anterolateral sectors. At the prostate apex and the urethral levels, the NVBs have two divisions: cavernous nerves (CNs) and corpus spongiosum nerves (CSNs). The CNs were a continuation of the anterior and anterolateral fibres around the apex of the prostate, travelling towards the corpora cavernosa. The CSNs were a continuation of the posterolateral NVBs, and they eventually reached the corpus spongiosum. The limitations of this study were the small number of specimens available and the lack of functional information. ConclusionsThe anterolateral position of CNs at the apex of the prostate and the autonomic innervation towards the corpus spongiosum via CSNs indicate possible ways to minimise the effect of prostate surgery on sexual function. The ideal dissection plane should probably include the preservation of the anterolateral tissues and fascias to avoid CN lesions. Anatomic knowledge gained from CAAD pertains directly to proper surgical technique and subsequent recovery of erectile function after RP.