Anatomical Observation Of Lumbar Nerve 6 And Identification Of The Neural Pathway Between Major Pelvic Ganglia And External Urethral Sphincter In SD Rat

Lower urinary tract dysfunction caused by Spinal cord and/or peripheral nerve injury is common in clinical practice, such as bladder dysfunction in patients with paraplegia, the coordination dysfunction of bladder and urethral sphincter caused by pelvic surgery or trauma, and seriously affected the patient's quality of life. The late complications, especially the urinary tract infection and renal failure, are the major cause of death of patients. To solve the medical problems, domestic and foreign scholars have done a lot of animal experiments and clinical research. However, since the innervation of the lower urinary tract is very complex and the most previous experiments confined to one or some certain parts of one or several nerve branches, the origination of such nerve fibers has not been very clear. In order to systematically understanding the innervation of the lower urinary tract, we have taken a more detailed study on the L6 which mainly dominated the lower urinary tract in SD rat by employing the microdissection technique; meanwhile, by means of neural tracking technology, it was found that the external urethral sphincter is not only innervated by the somatic nerves, but also by the postganglionic fibers of the major pelvic ganglion, which is also a new understanding to the traditional point of view.The dissertation is divided into two parts: Objective: Identifying the travelling line and the variation of the branches of the lumbar nerve 6 (L6) in SD rat , and observing the linkages between the branches of L6 and the other peripheral nerves, to provide some information on more detailed anatomy for neurourology research.Methods: Under the stereomicroscope, observe, measure and record the neural pathways, length, branch numbers and variation of L6 from origination of spinal cord to terminations in 50 male SD rats .Results: The ventral and dorsal roots of L6 were issued from the anterior horn and the dorsal horn of the spinal cord under the lower edge of L1 vertebral body, respectively, and ran within the spinal canal close to the ventrolateral and dorsolateral spinal dura mater to the lower edge of the L6 vertebral body with a total length of about 3.6cm, showing a imbricated arrangement from top to bottom with other nerve roots. At a distance of about 0.5cm away from the intervertebral foramen, L6 and the lumbosacral trunk travelled closely, and there was a contact between L6 and the lumbosacral trunk in a majority of specimens(89%). In the 95 specimens, L6 accepted the joining of a branch derived from the sacral nerve 1(S1) beyond the contact between L6 and the lumbosacral trunk. After issueing the pelvic nerve, the L6-S1 trunk (or L6) was referred to as the pudendal nerve. Then the pudendal nerve connected to the lumbosacral trunk to form a bridge-like structure, called the sacral plexus. The nerve branches of the sacral plexus travelling here were highly complicated. The major pelvic ganglion(MPG) was dominated by both the pelvic nerve and the hypogastric nerve. The postganglionic nerves distributed to the urinary bladder, vas deferens, seminal vesicle and cavernosum, etc.. Conclusion: 1. Inside the spinal canal, The ventral and dorsal roots of L6 had a long walking line , a large active range, and a imbricated arrangement with other nerve roots. So, it was easy to carry out operations such as replantation or reconstruction.2. Outside the spinal canal, there were many branches issued from L6. Since some branches were relatively thick, it was very suitable for the establishment of animal models of nerve injury.3. The variation of the branches ,which were issued from L6, and the contacts with the other peripheral nerves were obvious.4. The SD rats is a good animal model for the neurourological research.Partâ…¡Identification of the neural pathway between major pelvic ganglia and external urethral sphincter in SD ratObjective: To identify the neural pathway between major pelvic ganglion(MPG) and external urethral sphincter(EUS) using microanatomical and neural tracing technology in SD rat.Methods: Having exposed and observed the segment from MPG to EUS under a stereomicroscope, fluorogold(FG) and fast blue(FB) were respectively injected into the bladder detrusor and EUS for retrograde tracing, then detected the positive neurons in MPG. Wheat germ agglutinin-horseradish peroxidase(WGA-HRP) was injected into MPG, and positive nerve endings were detected in EUS. Cut off the contact at the junction of bladder base and EUS , and repeated the experiments above.Results: In the normal groups, a large number of FG and FB single-labled neurons have been identified under fluorescent microscope as well as a few double-labeled cells distributing in MPG; under optical microscope, the distribution of brown-black positive nerve endings within the EUS were numerous. In the joint-cut groups between bladder base and EUS, only FG single-labeled neurons were visible in the MPG but FB labeled neurons and no positive nerve endings were observed within the EUS.Conclusions: The neural conduction pathway, which may dominate the EUS and coordinate the activities of bladder detrusor and urethral sphincter during the process of urine collecting and voiding reflexes, between MPG and EUS evidently exists.