大鼠骶副交感核的形态学测量和三维重建

Morphological measurment and three-dimensional reconstruction of the sacral parasympathetic nucleus

目的:研究大鼠盆内脏神经的初级中枢骶副交感核(SPN)的形态学特征及空间三维立体结构,为准确定位SPN并探索其功能提供形态学依据,方法:经背侧入路显露S D大鼠的盆内脏神经,在其中枢断端采用Alexa594结合的霍乱毒素b(CTb)逆行示踪。将标记后的脊髓L_(6)~S_(1)节段分别进行连续的水平面和矢状面切片。荧光显微镜下观察CTb标记的神经元的形态、位置和结构。通过三维重建软件,从切片图像序列中模拟出SPN的三维模型。结果:CTb逆行标记的盆内脏神经的节前神经元主要分布于脊髓L_(6)~S_(1)节段的中间带外侧。这些神经元可分为3个亚群:外侧带位于SPN的外下部,大多是纺锤形双极神经元,树突沿灰质外侧缘指向前角方向;背侧带位于SPN的背上方内部,放射状分布的神经元的树突多沿后联合方向水平延展;中间带位于前两者之间,神经元的形态多样,以多极神经元为主。三维重建显示SPN呈“串珠样”结构。定位注射的理想的进针角度是与水平线60°,进针深度距离白质表面约为220~245μm。结论:SPN的定位和测量,为进一步研究其神经生理功能提供形态学方面的基础数据;三维重建可以从各个角度显示出SPN的结构特点,也可为准确定位注射提供参数。

Objective:To explore characteristics of the neurons and three-dimensional mode of sacral parasympathetic nucleus(SPN)in the primary central center of rat pelvic splanchnic nerve,in order to provide morphological data for locating accurately the SPN and exploring its function.Methods:The pelvic nerve of SD rats was dissected via the dorsal approach,and Alexa594 combined cholera toxin subunit b(CTb)was used to retrograde trace mark from the central end of the pelvic visceral nerve.The labeled L_(6)〜S_(1)segments of the spinal cord were sectioned in horizontal plane and sagittal plane,respectively.Fluorescence microscopy was used to observe the morphology,location and structure of the labeled neurons.Finally,the Three-dimensional model of SPN is simulated from the slice image sequence by using computer three-dimensional reconstruction techniques.Results:The retrograde labeled preganglionic neurons of the pelvic splanchnic nerve were mainly distributed in the lateral middle band of the spinal cord from L_(6)to S_(1),which can be assigned to three subgroups:The lateral band can be found at the outer base of SPN and comprises spindle-shaped bipolar neurons with dendrites that extend along the lateral margin of gray matter into anterior horn;the dorsal band located on the dorsal interior of SPN and comprises radially oriented neurons with dendrites that extend medially into the dorsal gray commissure;Neurons in the interband located between the lateral and dorsal band,which are mainly pleomorphic and multipolar ones.The spatial structure of SPN was showed as "strings of beads" by three-dimensional reconstruction.For stereotaxic microinjections,the ideal insertion angle is 60° from the horizontal line and the depth is about 220〜245μm from the surface of the white matter.Conclusion:These results will provide important data for SPN measurement and localization,and provide morphological basis for the further study of its physiological function.Three-dimensional reconstruction can display the structural characteristics of SPN from different angles,and also provide accurate parameters for injection.