Development of a Porcine Model to Study the Aortic Plexus and Innervation to the Internal Urethral Sphincter: Implications for Preventing Retrograde Ejaculation
Bibliographic record
Abstract
INTRODUCTION The sympathetic nerves and ganglia overlying the abdominal aorta in humans are symmetrically organized into a bilateral network called the aortic plexus that must be spared during retroperitoneal surgery in order to maintain antegrade ejaculation. It is well established that complete resection of the aortic plexus causes retrograde ejaculation (RE) that results from de‐innervation of the internal urethral sphincter (IUS). At present, however, it remains uncertain which specific nerves of the aortic plexus control the IUS, and thus, which nerves are important for ejaculation. To ultimately determine which nerves are imperative to maintain ejaculation, the present study aimed to first establish the pig as a comparable model of the human aortic plexus in both structure and function. It was our working hypothesis that the pig exhibits comparable anatomy in terms of gross organization, number of infrarenal splanchnic nerves and constituent ganglia, and that stimulation of the left and right hypogastric nerves (homologous to the human superior hypogastric plexus) would evoke contraction of the IUS. METHODS The porcine aortic plexus was examined in 18 boars by gross dissection followed by a histological examination to differentiate ganglia from nerve. Innervation of the IUS was examined using a lesion‐and‐test method, in which stimulation with a bipolar electrode was used to excite the hypogastric nerves distal to the caudal mesenteric ganglia before and after transection (n=5). RESULTS As predicted, the anatomy of the porcine aortic plexus appeared comparable to humans, exhibiting two bilateral cords that were supplied by two or more infrarenal lumbar splanchnic nerves. Right and left caudal mesenteric and spermatic ganglia were invariably observed adjacent to their respective arteries, and given their topography within the plexus, they appear homologous to the prehypogastric, inferior mesenteric and spermatic ganglia in humans, respectively. At the junction of the upper infrarenal lumbar splanchnic nerves, two additional ganglia were observed within the cords of the porcine aortic plexus (prevalence right = 4/8; prevalence left = 3/8); these structures have not been reported in humans. Electrostimulation of each hypogastric nerve evoked bladder neck contraction (ΔP right = 6.2 ± 2.2 mmHg, ΔP left = 4.5 ± 2.2 mmHg), which was abolished following transection. CONCLUSIONS Collectively, our results confirm that the pig represents an effective preclinical model for studying not only the structure and normal function of the aortic plexus, but also the implications of unintended surgical trauma on the delicate nerves controlling ejaculation. Support or Funding Information This work is supported by CIHR
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".