Djibril Diallo

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

BACKGROUND Detailed knowledge of the distribution and distal course of periprostatic nerves is essential to improve functional outcomes (erection and continence) after radical prostatectomy (RP). OBJECTIVE To 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 PARTICIPANTS Serial 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. MEASUREMENTS We 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 LIMITATIONS Periprostatic 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. CONCLUSIONS The 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.

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

ObjectiveClassic 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.Materials and methodsSerial 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.ResultsThe 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.ConclusionThe 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.

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 200 μm. The first section was stained with hematoxylin‐eosin or Massons 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.

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 30 weeks of gestation. Sections were treated with histological staining [hematoxylin‐eosin (HE) and Massons 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.

Functional and structural microanatomy of the fetal sciatic nerve

The ultrastructure of a nerve has implications for surgical nerve repair. The aim of our study was to characterize the fascicular versus fibrillar anatomy and the autonomic versus somatic nature of the fetal sciatic nerve (SN).

The Visceromotor and Somatic Afferent Nerves of the Penis

INTRODUCTION Innervation of the penis supports erectile and sensory functions. AIM 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. METHODS Penises obtained from five adult cadavers were studied via computer-assisted anatomic dissection (CAAD). MAIN OUTCOME MEASURES The number of autonomic and somatic nerve fibers was compared using the Kruskal-Wallis test. RESULTS 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. CONCLUSIONS 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.