Morphology of nervous lesion in the spinal cord and bladder of fetal rats with myelomeningocele at different gestational age

ObjectiveTo analyze the development and innervation of bladder smooth muscle and lesions of the spinal cord in fetal rats with meningomyelocele (MMC) at different gestational ages and to investigate interactions between spinal cord lesions and bladder.MethodEach fetus was assigned to the MMC group or the normal group. Each group was further divided into three subgroups by gestational age: E16, E18, and E20 (embryonic days 16, 18, and 20, respectively). α-Actin and neurotubulin-β-III were analyzed in the bladder, and GFAP and VAChT were analyzed in the lumbosacral spinal cord by immunohistochemistry. Photographs were taken to determine the integrated optical density of each sample.ResultsNeurotubulin-β-III was significantly lower in the MMC group than in the normal group at all fetal ages. Abundant α-actin was detected in both groups at all fetal ages. No significant difference was found between the MMC group and the normal group at any fetal age. At E16 and E18, no GFAP-positive astrocyte was detected in the MMC group or the normal group. At E20, numerous GFAP-positive astrocytes were detected in the MMC group, with significant difference from the normal group. VAChT was detected less in the MMC group than in the normal group at all fetal ages with significant differences.ConclusionBladder smooth muscle of fetal MMC rat seems morphologically normal in development, while the innervation of the bladder smooth muscle is markedly decreased centrally and peripherally. Astrocytosis appears at a later embryonic stage, which could be a concern in the nerve repair of the spinal cord.