BACKGROUND: Studies have demonstrated that selective innervation of the sacral nerve tract tothe bladder plays an important role in bladder functional reconstruction following spinal cord injury.However, there are very few studies reporting detailed morphological characteristics of urogenitalcenter and lumbosacral nerve roots.OBJECTIVE: To analyze the spinal cord segment of the lumbosacral spinal cord urogenital center,and to observe morphological characteristics.DESIGN, TIME AND SETTING: A neuroanatomical study was performed at the Laboratory ofNeuroanatomy, Peking University Health Science Center between September 2007 and March2008.MATERIALS: Horseradish peroxidase-conjugated cholera toxin B subunit (CB-HRP) waspurchased from Sigma, USA; surgical microscope was purchased from Zhenjian Zhongtian OpticalInstrument, Jiangsu Province, China; BCL-420 biological and functional experimental system waspurchased from Taimeng Science and Technology, Sichuan Province, China.METHODS: A total of 36 adult, Sprague Dawley rats were randomly assigned to groups A (n = 10),B (n = 10), C (n = 10), and D (n = 6). CB-HRP (3%, 10-15 μL) was injected into the bladder detrusormuscle (group A), external urethral sphincter (group B), and perineal muscles (group C),respectively. Rats in group D were not given any treatments.MAIN OUTCOME MEASURES: At 72 hours after CB-HRP injection, CB-HRP-positive neurons wereanalyzed in lumbosacral segments using 3, 3’, 5, 5’-tetramethylbenzidine staining and an Olympusoptic microscope, while anatomical structures in the respective spinal nerve tract were observedusing a surgical microscope.RESULTS: CB-HRP-positive neurons were distributed in the L_6 S_1 segments of the spinal cord, andneurons primarily innervating the bladder detrusor muscle were located at the sacralparasympathetic nucleus and the intermediolateral nucleus. In addition, neurons that primarilyinnervate the external urethral sphincter and perineal muscles were observed in the ventrolateralportion (Onuf’s nucleus). The lumbar-sacral nerve roots were composed of varying nerve tracts, i.e.,they were typically divided into 1-2 sub-bundles, and the sub-bundles were then divided into 2-3tiny bundles. There were extensive fibro-connections between the rootlets.CONCLUSION: The urogenital center in Sprague Dawley rats was located in the L_6-S_1 segments ofthe spinal cord, and the rootlets were clearly observed. Therefore, this rat experimental model couldbe utilized for highlv selective anterior/posterior rhizotomy. BACKGROUND: Studies have demonstrated that selective innervation of the sacral nerve tract tothe bladder plays an important role in bladder functional reconstruction following spinal cord injury. Now that there are very few studies studies full morphological characteristics of urogenital center and lumbosacral nerve roots.OBJECTIVE: To analyze the spinal cord segment of the lumbosacral spinal cord urogenital center, and to observe morphological characteristics. DESIGN, TIME AND SETTING: A neuroanatomical study was performed at the Laboratory of Neuroanatomy, Peking University Health Science Center between September 2007 and March 2008. Majories: Horseradish peroxidase- BCL-420 biological and functional experimental system waspurchased from Taimeng Science and Technology, Sichuan Province, China. Biochimica et al. METHODS: A total of 36 adult, Sprague Dawley rats were randomly assigned to groups A (n = 10), B (n = 10), C (n = 10), and D μL) were injected into the bladder detrusormuscle (group A), external urethral sphincter (group B), and perineal muscles (group C), respectively. Rats in group D were not given any treatments. MAIN OUTCOME MEASURES: At 72 hours after CB -HRP injection, CB-HRP-positive neurons wereanalyzed in lumbosacral segments using 3, 3 ’, 5’-tetramethylbenzidine staining and an Olympusoptic microscope, while anatomical structures in the respective spinal nerve tract were observedusing a surgical microscope .RESULTS: CB -HRP-positive neurons were distributed in the L_6 S_1 segments of the spinal cord, andneurons initially innervating the bladder detrusor muscle were at the sacral parasympathetic nucleus and the intermediolateral nucleus. In addition, neurons that ofinnervate the external urethral sphincter and perineal muscles were observed in the ventrolaterThe lumbar-sacral nerve roots were composed of varying nerve tracts, ie, they were typically divided into 1-2 sub-bundles, and the sub-bundles were then divided into 2-3tiny bundles. There are extensive fibro-connections between the rootlets. CONCLUSION: The urogenital center in Sprague Dawley rats was located in the L_6-S_1 segments of the spinal cord, and the rootlets were clearly observed. Thus, this rat experimental model could be utilized for highlv selective anterior / posterior rhizotomy .