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PubMed2001

Functional morphology of venous structures associated with the male and female reproductive systems in Florida manatees (Trichechus manatus latirostris).

The reproductive organs of Florida manatees (Trichechus manatus latirostris) are surrounded by thermogenic locomotory muscles and insulating fat. Manatees are reported to maintain core body temperatures of 35.6 degrees -36.4 degrees C, temperatures known to interfere with production and maturation of viable sperm in terrestrial mammals. We describe two novel venous plexuses associated with the manatee epididymis. Each epididymis is located in a hypogastric fossa at the caudolateral extremity of the abdominal cavity. Each hypogastric fossa is lined by an inguinal venous plexus that receives cooled blood from a superficial thoracocaudal plexus. We conclude that male manatees may prevent hyperthermic insult to their reproductive tissues by feeding cooled superficial blood to venous plexuses deep within their bodies. Female manatees also possess hypogastric fossae and venous structures similar to those found in male manatees. The ovaries, uterine tubes, and distal tips of the uterine horns are located in the hypogastric fossae. We suggest that the thermovascular structures we describe also prevent hypothermic insult to female manatee reproductive tissues. The venous structures in manatees are functionally similar to structures associated with reproductive thermoregulation in cetaceans and phocid seals. Thus, these thermovascular structures appear to be convergent morphological adaptations that occur in three clades of diving mammals with independent evolutionary histories.

Animals↗

PubMedDate not supplied

Avoiding long-term disturbance to bladder and sexual function in pelvic surgery, particularly with rectal cancer.

Urinary and sexual dysfunction are common problems after rectal cancer surgery, and the likely cause is damage to the pelvic autonomic nerves during surgery. In recent years, attention has been focused on preserving the autonomic nerves through a technique which is usually combined with total mesorectal excision or radical pelvic lymphadenectomy. The autonomic nerves consist of the paired sympathetic hypogastric nerve, sacral splanchnic nerves, and the pelvic autonomic nerve plexus. We will demonstrate the anatomy of the pelvic autonomic nerves and the relation of these nerves to the mesorectal fascial planes, and review the medical literature on sexual and urinary dysfunction after rectal cancer surgery with and without autonomic nerve preservation.

Autonomic Nervous System↗

PubMed1985

The components of the hypogastric nerve in male and female guinea pigs.

A quantitative study has been made of the neural components of the hypogastric nerves of male and female guinea pigs using retrograde transport of horseradish peroxidase (HRP) to identify the population of neurones projecting in the nerve trunk, and electronmicroscopic analysis of the myelinated and unmyelinated axons present. Application of HRP to the transected axons of the hypogastric nerve labelled the cell bodies of sensory neurones in lumbar and sacral dorsal root ganglia, preganglionic neurones in the lumbar and sacral spinal cord, and postganglionic neurones in the inferior mesenteric ganglion and in the lumbar paravertebral chain; some ganglion cells of the pelvic plexus were also labelled. The number and distribution of each type of neurone with axons in the hypogastric nerve differed between the sexes: in particular, about twice as many preganglionic axons were present in the male as in the female.

Afferent Pathways↗

PubMed1969

Transmission from pregnanglionic fibres in the hypogastric nerve to peripheral ganglia of male guinea-pigs.

1. Intracellular records were obtained from ganglion cells of the pelvic plexus of male guinea-pigs.2. The input resistance of cells which responded to intracellular stimulation varied from 40 to 150 MOmega. Slope resistance decreased when the membrane was hyperpolarized. Time constants varied from 5 to 200 msec. Resting membrane potentials ranged from 40 to 70 mV.3. Action potentials in response to direct stimulation were followed by a prolonged phase of after-hyperpolarization.4. A second type of cell was also impaled which did not respond to electrical stimulation. These cells had resting membrane potentials in the range 60-70 mV, input resistances of less than 20 MOmega and time constants of less than 3 msec.5. In most ganglion cells, stimulation of the hypogastric nerve evoked action potentials which were often followed by a secondary phase of depolarization indicating continuing transmitter action.6. Orthodromic responses were generally ;all-or-nothing' and could not be graded with changes in stimulus strength. The latency of orthodromic responses indicated that ganglion cells were innervated by both B and C fibres in the hypogastric nerve.7. Orthodromic responses were blocked by tubocurarine, 5 x 10(-5) g/ml., and dihydro-beta-erythroidine, 10(-5) g/ml.8. Spontaneous, excitatory post-synaptic potentials of up to 4.8 mV in amplitude were observed. The frequency of their discharge was greatly increased by repetitive stimulation of the hypogastric nerve.9. The ultrastructure of the pelvic ganglia was studied by electronmicroscopy. Two types of ganglion cell process were observed, fine (0.1 mu) branching tufts thrown up from the soma within the surrounding capsule and longer, thicker (1 mu) extracapsular processes. Synapses were found to occur most frequently between the varicose terminal segments of preganglionic axons and the small intracapsular processes.10. Similarities between the properties of the pelvic ganglia innervated by the hypogastric nerve and those of the parasympathetic division of the autonomic nervous system are discussed.

Action Potentials↗

PubMed2000

Extrafascial excision of the rectum: surgical anatomy of the fascia propria.

PURPOSE: It is now agreed that it is of vital importance to maintain the fascia propria as an intact envelope around the mesorectum to prevent tumor spillage while performing rectal excision for cancer. There are several surgical techniques described to achieve an intact fascial envelope, each arising from differing descriptions of the fascia propria of the rectum. The aim of this study was to describe the detailed surgical anatomy of the fascia propria. METHODS: Thirteen rectal specimens surgically removed by the technique of extrafascial excision were subjected to gross inspection, dissection, and histologic and electron microscopic examination. The attachments, thickness, and composition of the fascia propria were determined. RESULTS: The fascia propria is a continuous fascial sleeve surrounding the rectum and mesorectum that can be dissected as a complete "sock" off a fresh extrafascial specimen. It is 154 (+/- 1 standard deviation = 61-391) microm thick, is thinner anteriorly than posteriorly (P < 0.05), and is composed predominantly of collagen. It can be identified surgically at the pelvic brim as a shiny membrane and lies inside the hypogastric nerves and the pelvic plexuses. CONCLUSION: The fascia propria forms a sleeve around the mesorectum, offering a surface against which to dissect, enabling safe removal of the rectum with its intact mesorectum while preserving the autonomic nerves of the pelvis. The term "extrafascial excision" highlights the importance of the fascia propria in this operation.

Adult↗

PubMed1989

Mechanically evoked responses of afferent fibres innervating the guinea-pig's ureter: an in vitro study.

1. Electrophysiological recordings from ureteric mechanosensitive afferent fibres were performed using an in vitro preparation of the guinea-pig ureter and associated nerves. Single-unit recordings were obtained from small ureteric nerves arising from the inferior mesenteric ganglion, the hypogastric nerve or the pelvic plexus. The fibre composition of these ureteric nerves was also examined by electron microscopy. 2. In two ureteric nerve bundles, which were taken as representative of the maximal and minimal size of nerves used in the electrophysiological recordings, the number of nerve fibres was found to be 417 and 48, respectively. In the bigger nerve 12% of the fibres were small myelinated and the rest unmyelinated. The smaller nerve consisted of unmyelinated fibres only. 3. Electrophysiological recordings were made from sixty-seven mechanosensitive afferent fibres. The conduction velocities (CV) of forty-two of them were determined and all were found to be in the C fibre range (mean CV, 0.4 m/s). Of 119 additional fibres which were not further characterized 112 were C fibres (mean CV, 0.51 m/s) and seven were A delta fibres (mean CV, 3.78 m/s). 4. Mechanosensitive units were classified into two groups according to their ability to respond to contractions of the ureter: (i) U-1 units (9% of all mechanosensitive units) responded to contractions of the ureter and did not show on-going activity or after-discharges to mechanical stimulation. They had low thresholds to intraluminal distension (mean, 8 mmHg) and responded with a short latency to pressure stimuli. (ii) U-2 units (91% of all mechanosensitive units) did not respond to contractions of the ureter, had spontaneous activity between 0 and 2.4 Hz and exhibited after-discharges to mechanical stimuli lasting up to several minutes. They responded after a long latency (greater than 3 s) to distensions in the range of 5-30 mmHg. 5. The level of spontaneous activity and the pressure thresholds of the U-2 units were found to be different depending on whether or not the ureter was perfused intraluminally. Thus U-2 units recorded with intraluminal perfusion had a lower rate of on-going activity and higher threshold to intraluminal distension than U-2 units recorded without intraluminal perfusion. 6. Movement of an intraluminal glass bead under the receptive field of the units evoked strong responses in nine of eleven U-2 units tested as soon as their receptive fields were reached. 7. Our results demonstrate the existence of two classes of mechanosensitive afferent fibres in the guinea-pig ureter.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed2001

Sympathetic blockade for the relief of chronic pain.

The sympathetic blocks are useful in many ways for relief of chronic pain. The sympathetic block can be caused at pre- and paravertebral sympathetic ganglia eg, stellate ganglia, coeliac plexus and lumbar sympathetic ganglia. Indications for sympathetic blockade are: Complex regional pain syndrome, phantom limb pain, central pain, acute pancreatitis, pancreatic cancer and cancer pain from upper abdominal viscera. Stellate ganglion blockade is required for the diagnosis, prognosis and therapy for painful and other conditions associated with sympathetic dysfunctions of head, neck and upper extremity. Coeliac plexus block is indicated in pain due to intra-abdominal cancer, stemming from organs innervated by coeliac plexus. Lumbar sympathetic block is indicated for diagnosis, prognosis and therapy for painful and other conditions associated with sympathetic dysfunctions like complex regional pain syndrome I and II, herpes zoster, amputation stump pain and inoperable peripheral vascular vasospastic diseases of the lower limb. Indications for superior hypogastric block are the prognostic and therapeutic purposes of cancer pelvic organs--uterus, cervix, bladder, prostate, urethra, testes and ovaries.

Anesthetics, Local↗

PubMed1975

Peripheral nerves controlling the closure of internal urethral orifice during ejaculation.

The peripheral nervous pathways controlling seminal emission and closure of the internal urethral orifice during ejaculation were examined experimentally using male adolescent dogs. The experimental methods were measurement of the contraction of the internal urethral orifice and measurement of the change of the posterior urethral pressure induced by selective stimulation of the nerves related to the hypogastric nerve. Further, the change of actual ejaculation caused by manual stimulation of the penis was observed after excision of the nerves. Results included the following: (1) The seminal emission and the closure of the internal urethral orifice on ejaculation were controlled by the hypogastric nerve. (2) The nerve fibers which controlled these two phenomena took different paths above the lower mesenteric plexus. (3) Seminal emission was controlled by the splanchnic nerves which originated from the lower thoracic and upper lumbar ganglia of the sympathetic trunk, and the closure of the internal urethral orifice by those which originated from the lower lumbar ganglia of the trunk.

Animals↗

PubMed2001

Sympathetic efferent pathways projecting to the vagina in the dog.

The level of the thoracolumbar sympathetic outflow projecting to the vagina and the laterality of the signals passing through the splanchnic nerves to the vagina have not been well understood. This study was undertaken to explore the sympathetic innervation of the canine vagina by measuring intraluminal pressure of the vagina and contraction of the vaginal wall by electrical stimulation of each of the thoracolumbar splanchnic nerves with or without transection of unilateral hypogastric nerve (HGN). The 2nd-4th lumbar splanchnic nerve (LSN) stimulation elicited elevation of intraluminal pressure of the vagina and contraction of the vaginal wall. In contrast, intermesenteric plexus stimulations caused no response in both the vaginal pressure and the wall itself. On the right side, 12 of 27 LSNs that were stimulated elicited elevation of vaginal pressure and 16 of 32 LSN stimulations caused contraction of the wall, 10 increases in tension and 6 reductions. On the left side, 14 of 26 LSN stimulations elicited elevation of vaginal pressure and 12 of 27 LSN stimulations caused contraction of the wall, 5 increases in tension and 7 reductions. After transection of the right HGN, 6 of 14 right LSN stimulations elicited elevation of vaginal pressure and 10 of 15 right LSN stimulations caused contraction of the wall, 9 increases in tension and 1 reduction. After transection of the left HGN, 13 of 19 left LSN stimulations elicited elevation of vaginal pressure and 10 of 18 left LSN stimulations caused contraction of the wall. 4 increases in tension and 6 reductions. The results indicate that each of the L2-L4 LSNs on either side sends signals to the canine vagina via multiple routes with a crossing site at the level of the caudal mesenteric plexus (CMP).

Animals↗

PubMed1991

The sympathetic role as an antagonist of erection.

The effects of the lumbar and pelvic sympathetic system on penile erection were studied in a canine model. Erection was induced by cavernous nerve stimulation and detumescence by sympathetic trunk stimulation. Erection induced by cavernous nerve stimulation normally subsides slowly. After discontinuation of electrical stimulation the intracavernous pressure drops within a mean of 291 s to 50% and after a mean of 372 s to 10% of the highest level. However, stimulation of the sympathetic trunk at the level of L4-S1 applied directly after discontinuation of cavernous nerve stimulation accelerated this drop of intracavernous pressure significantly: to 50% after a mean of 19 s and to 10% after a mean of 36 s. If stimulation of the sympathetic trunk was initiated 20 s before cavernous nerve stimulation, the pressure rise was aborted completely. Neurostimulation of the hypogastric nerves alone or in combination with cavernous nerve stimulation did not change the intracavernous pressure. These results were not altered after neurotomy of the pudendal or hypogastric nerves. The main pathway of the fibers from the sympathetic trunk to the penis seems to run via the pelvic plexus. The stimulation voltage and frequency to induce erection or detumescence were equivalent. Our results suggest that an elevated central sympathetic tone may be one of the causes of psychogenic impotence.

Animals↗

PubMed1988

Neurons projecting rostrally in the hypogastric nerve of the cat.

Afferent, pre- and postganglionic nerve cell bodies projecting rostrally in the hypogastric nerve have been labelled retrogradely with horseradish peroxidase, in order to study number and location of these neurons. Labelled somata were found in the ganglia of the pelvic plexus, in sacral spinal ganglia and in the sacral spinal cord. They were located mainly ipsilateral with a maximum of afferent and preganglionic neurons at the segmental level S2. The numbers of labelled cells were small (less than 3.5% of all axons in the hypogastric nerve) and varied considerably between animals. Therefore this population of neurons is probably small and of limited functional significance. Enteric neurons (probably afferent) that have their cell bodies within the pelvic viscera and project rostrally in the hypogastric nerve to the inferior mesenteric ganglion were not included in this study and might be of more functional importance.

Afferent Pathways↗

PubMed1985

Three serial neurones in the innervation of the colon by the sacral parasympathetic nerve of the dog.

Electrophysiological and histological techniques were used to study the nature of the innervation of the colon by the sacral parasympathetic nerve of the dog. Many cells which incorporate horseradish peroxidase (HRP) were observed in ganglia of the pelvic plexus, but not in the sacral cord, after HRP was injected into the wall of the distal colon. Stimulation of the pelvic ganglia by an application of dimethylphenylpiperazinium contracted the distal colon. The contraction was reduced by nicotine applied to the colon. Compound action potentials in responses of rectal strands of the pelvic nerve to stimulation of the sacral ventral roots decreased or disappeared after hexamethonium bromide (C6) was applied to the pelvic plexus. Conduction velocities of the potentials showed that most of the preganglionic fibres were B fibres, and nearly all the post-ganglionic fibres were C fibres. Many C fibres were observed by electron microscopy in the rectal strands after degeneration of the pelvic and hypogastric nerves. Stimulation of such rectal strands caused a contraction of the colon, which diminished after C6 was applied to the distal colon. These results show that the sacral parasympathetic nerve innervating the colon comprises three serial neurones located in the sacral spinal cord, the pelvic plexus and the myenteric plexus.

Action Potentials↗

PubMed1982

Structural studies on the connectivity of the inferior mesenteric ganglion of the guinea pig.

After injection of horseradish peroxidase (HRP) into the inferior mesenteric ganglion (IMG) of the guinea pig, labeled cell bodies were found in the solar plexus ganglia, the ganglia of the pelvic plexus and in the nodose ganglia as well as in the spinal cord and dorsal root ganglia at the T13-L4 levels. By using the fluorescent tracer True blue, labeled cell bodies could also be detected in the myenteric and submucosa ganglia of the distal colon. Application and uptake of HRP by the colonic nerves resulted in labeling of cell bodies in the dorsal root ganglia, the IMG and in the solar plexus ganglion complex indicating that the latter neurons send their axons in the intermesenteric nerve through the IMG to continue in the colonic nerves to the distal colon. When HRP was applied and diffused into the hypogastric nerves labeled cell bodies were seen in the IMG, the dorsal root ganglia and in the preganglionic nuclei of the lumbar spinal cord with 50% of the labeled neurons located dorsal and dorsolateral to the central canal. The finding of such a diversity in the nerve supply to the IMG, supports the view that the ganglion plays an important role in the integration of visceral reflexes.

Animals↗

PubMed1997

Urinary bladder response to hypogastric nerve stimulation after bilateral resection of the pelvic nerve or spinal cord injury in rats.

BACKGROUND: We examined the mechanism of urinary bladder motility return after bladder areflexia induced by interruption of the sacral parasympathetic outflow to the urinary bladder following damage to the sacral cord or pelvic nerves in the rat. METHODS: The L6 and S1 nerve bundles were resected near the vertebrae, and bilateral pelvic nerve resections (PNR) performed. Spinal cord injury (SCI) was performed by means of a legion generator at the T12 vertebra. Thirty days after PNR and SCI, cystometrograms were recorded under anesthesia. RESULTS: In all rats subjected to PNR or SCI, overflow incontinence continued, yet some rats subjected to SCI recovered within 2 weeks after the operation. Cystometrograms showed that repetitive bladder contractions appeared in rats subjected to SCI irrespective of hypogastric nerve (HGN) innervation, while bladder contractions did not appear in rats subjected to PNR. Electrical stimulation of the HGN induced higher bladder pressure elevation in rats who underwent PNR than in rats subjected to SCI. CONCLUSIONS: These results suggest that the generation of repetitive bladder contractions induced by bladder distention after bladder areflexia requires the presence of intact pelvic nerves that transmit sacral cord-originating excitatory information to the bladder. However, the HGN system and functioning pelvic nerve ganglia are not involved in this process. Also, the connection from the preganglionic HGN to the postganglionic parasympathetic nerves in the pelvic plexus did not form after PNR.

Animals↗

PubMed1993

Control of bilateral seminal emissions from ejaculatory ducts by a lumbar splanchnic nerve.

To investigate the route of efferent signals for seminal emissions from ejaculatory ducts (SEEDs), canine lumbar splanchnic nerves (LSNs) were electrically stimulated. SEED was confirmed by visual verification of seminal flow into the exposed posterior urethra. In intact dogs, electrical stimulation of an LSN caused bilateral SEEDs in 13 of 16 dogs examined, with a greater volume at the stimulated side. After transection of a unilateral hypogastric nerve, bilateral SEEDs occurred by electrical stimulation of the contralateral LSN in 11 of 14 dogs with a greater volume at the stimulated side and by the stimulation of the ipsilateral LSN in 13 of 15 dogs with a greater volume at the contralateral side. Contraction pressure of the epididymal tail under the same conditions harmonized with the above results. We conclude that each LSN generates bilateral SEEDs by sending signals to bilateral epididymal tails and that some of the signals through each LSN cross to the other side at the caudal mesenteric plexus and/or the prostatic plexus.

Animals↗

PubMed1999

Effects of hypogastric neurectomy on escape responses to uterine distention in the rat.

Anatomical data indicate that the rat uterine horn is innervated primarily by afferent fibers in the hypogastric nerves, suggesting that hypogastric neurectomy, but not pelvic or pudendal neurectomy, should eliminate behavioral responses to uterine horn stimulation. To test this hypothesis, detection and escape responses of rats to different volumes of uterine horn distention (via an indwelling intrauterine balloon) were compared before and after bilateral hypogastric (n = 9), sham-hypogastric (n = 3), pelvic (n = 3), or pudendal (n = 2) neurectomies. As predicted, sham-hypogastric, pelvic, and pudendal neurectomies had no effect on the rats' responses. However, although hypogastric neurectomy completely eliminated responses in five rats whose postmortem evaluation revealed no signs that the uterine balloons had evoked any pelvic pathophysiology, the neurectomy had no effect on the responses of an additional four rats. Postmortem evaluation of these rats revealed gross signs of severe pathology in the vicinity of the balloon in two rats, and evidence that the balloon had shifted caudally so that it was stimulating the cervix rather than the uterine horn in a third. In the fourth rat, pathophysiology had been deliberately induced by the prior implantation of a small pellet that released approximately 1 microg/day of prostaglandin PF2alpha over the uterine horn. Similar findings have been reported in clinical studies on the efficacy of hypogastric ('presacral') neurectomy for dysmenorrhea. Together, the findings support the hypothesis that the major source of afferent innervation of the uterine horn in healthy rats and women is the hypogastric nerve but that the situation changes under conditions of pelvic pathology. Such changes could include additional activation of afferent fibers in nerves that supply other pelvic organs, activation by the uterine pathophysiology of latent uterine innervation from afferent fibers in the pelvic, vagus or ovarian plexus nerves, or some form of central sensitization.

Animals↗

PubMed2000

[Anatomic and clinical evidence of intrapelvic pudendal nerve and its relation with striated sphincter of the urethra].

OBJECTIVE: To demonstrate that somatic innervation of the urethrae striate sphincter is intrapelvic and not through an internal pudendal nerve, an extrapelvic nerve in its entire path. To study the relationship of the pelvic plexus with genito-urinary organs and its surgical implications. METHODS: 6 embryos and 2 fetuses, sliced and stained with techniques suitable for nervous structures were studied. Sequential observation of the pelvic plexus structures and the internal pudendal nerve was carried out using light microscopy. Three-dimensional reconstruction of the two fetuses was performed to study the relationships of these structures with the genito-urinary organs. RESULTS: A nervous branch was identified in the 19, 25 and 30 mm long specimens that started at the internal pudendal nerve and joined the hypogastric ganglion close to the site of pelvic nerves binding. Hypogastric ganglion efferent branches penetrating the striate sphincter after a short descendent run were seen in the 30 and 39 mm embryos. CONCLUSIONS: Our findings confirm that the urethrae striate sphincter received the autonomous and somatic innervation from the pelvic plexus and, therefore, is susceptible to damage during cancer related surgery of the pelvic organs. An improved knowledge of these structures and the use of nerve preservation surgical techniques can reduce the incidence of post-operative incontinence in this type of surgery.

Humans↗

PubMed1997

[The regeneration patterns of the canine hypogastric nerve when transplanted into the wall of the large intestine].

Findings of the study on the dog hypogastric nerve regeneration after implantation in caudal large intestine distal region are presented. Not only occurrence of the implanted nerve structure repair was shown, but also its assistance to formation of a well-developed neurovascular plexus in large intestine wall. Regenerated nerve fibres from the nervous plexus that forms in the epineurium of the implanted nerve invade the wall of large intestine. These data indicate the formation of an intramural nervous apparatus in large intestine wall providing additional neurotrophic regulation of an organ.

Animals↗