Leg dysfunctions in a chick model of spina bifida aperta

在汉堡期和汉米尔顿期的18、19期，采用切开胚胎神经管顶板的方法制备了先天性脊柱裂雏鸡。切口长度超过5和7节时，100%的雏鸟出现sba样畸形。SBO鸡没有表现出任何症状，而SBA鸡表现出腿部肌肉麻痹和激动剂和拮抗剂腿部肌肉不平衡。这些SBA雏鸡的病变位于产生运动神经元的脊髓节段，运动神经元支配功能失调的肌肉。组织学分析显示，与正常雏鸡相比，SBA雏鸡损伤部位的小脊髓中间神经元数量较少，而大脊髓运动神经元数量无明显差异。这种SBA模型的腿部功能障碍可能是由于脊髓节段中含有支配功能障碍肌肉的运动神经元的中间神经元数量较少。该模型有助于研究SBA雏鸡腿部功能障碍的病理机制。我们用抗胰岛-1单克隆抗体免疫组化染色检测SBA神经管。比较SBA组和对照组腰3椎体等效位置上胰岛1阳性运动神经元的数量和分布。在E4和E4.5时，SBA组运动神经元数量少于对照组。E6时，SBA组与对照组胰岛1阳性神经元数量差异无统计学意义。此外，SBA组在E6时胰岛1阳性细胞的分布也与对照组不同。这些结果表明，SBA对运动神经元的发育有延迟作用。

We created chicks with spina bifida aperta (SBA) by incising the roof plate of the neural tube of embryos at Hamburger and Hamilton stage 18 or 19. Incision over the length of five and seven somites caused SBA-like malformation in 100% of the hatchlings. The SBO chicks exhibited no symptoms, whereas the SBA chicks exhibited paralysis of a leg muscle and imbalance between an agonist and an antagonist leg muscles. Lesions in these SBA chicks were located in the spinal segments that give rise to motor neurons that innervated the dysfunctional muscles. Histological analysis revealed that there were fewer small spinal interneurons at the site of the lesion in SBA chicks than in the normal chicks and that there was no such difference in the number of the large spinal motor neurons. Leg dysfunctions in this model of SBA may be attributable to the smaller number of interneurons in the spinal segments that contain motor neurons that innervate the dysfunctional muscle. This model may facilitate studies of the pathological mechanisms that lead to leg dysfunctions in SBA chicks. We examined the SBA neural tube in by immuno- histochemical staining with the monoclonal antibody against Islet-1. The number and distribution of the Islet-1 positive motoneurons were determined at the position equivalent in the Lumbar 3rd vertebra and compared between SBA groups and control groups. On E4 and E4.5, the motoneuron number in the SBA group was less than that in the control group. On E6, the difference in the numbers of Islet-1 positive neuron between SBA group and control group was not significant. Moreover, the distribution of the Islet-1 positive cells in SBA group was different from that of control group on E6. These results suggest that the development of motoneuron is delayed in the chick embryos with SBA.