神经示踪定位SD大鼠长下行脊髓固有神经元胞体及其轴突投射的解剖位置

目的 利用神经示踪技术探讨SD大鼠长下行脊髓固有神经元及其轴突投射的解剖位置.方法 将荧光金(FG)注射入第1腰髓(L1)节段逆行标记大鼠下行脊髓固有神经元(DPNs)胞体;将顺行神经示踪剂生物素葡聚糖胺(BDA)注射到脊髓第3和第4颈髓处标记此处的DPNs胞体及其长下行脊髓固有束(LDPT).固定取材与切片染色后,检...

Nerve tracing the anatomical location of long descending propriospinal neurons and their axonal projections in SD rats

Objective The study investigated the anatomical location of long descending propriospinal neurons and theiraxonal projections in SD rats by anterograde and retrograde nerve tracing.Methods The retrograde nerve tracer Fluoro-Gold(FG)was injected into the 1 st lumbar(L₁)segment of spinal cord by stereotaxic apparatus to label the somas of the de-scending propriospinal neurons(DPNs)in rats. The anterograde tracer biotin dextran amine(BDA)was injected into thecervical enlargement(C3-C4)of spinal cord to mark the propriospinal neurons and their long descending propriospinal tract(LDPT)of spinal cord. After 7 days and 14 days,the samples were fixed and sectioned,and then performed the immunoflu-orescence histochemical staining. The distribution and quantity of FG-labeled DPNs in the gray matter of the cervical spinalcord were detected under the fluorescence confocal microscope,and the axonal number and their innervation of BDA-labeledLPDT projecting to the thoracolumbar segment of spinal cord were also detected.ResultsThe FG-labeled DPNs were main-ly distributed in the Ⅶ and Ⅷ lamina of the cervical spinal cord,a few FG-labeled DPNs were also found in III-VI and Xlaminas. The result of statistical analysis showed that there was no statistical difference in the number of DPNs co-labeled byFG and PI among the C₁-C₆ segments of spinal cord. The BDA-labeled LDPT was mainly distributed in both sides and ventralside of the white matter of spinal cord,and the axonal index of BDA-labeled LDPT in the white matter of T8 and T10 spinalcord[(61.19±8.61)% and(35.55±7.30)%,respectively]was significantly higher than that in the L₁ spinal cord(12.05±10.04)%(P<0.05). The BDA-labeled LDPT axons mainly project to the thoracic spinal cord and innervate the neurons inthe IV-X laminas,and a few BDA-labeled axons also project to L₁ spinal cord and innervate these neurons in the VII-IX lam-inas of L₁ spinal cord. The result of statistical analysis showed that the number of BDA-labeled axons in the gray matter of T8 and T10 spinal cord(41.47±20.33 and 24.87±15.80,respectively)was significantly higher than that in the L₁ spinal cord(7.40±4.88)(P<0.05).ConclusionThe somas of the Long descending propriospinal neurons were mainly distributed in the Ⅶ and Ⅷ lamina of spinal gray matter of the cervical enlargement in SD rats. The long descending propriospinal tractcan project to the thoracolumbar segments and innervate the neurons in the IV-X laminas of spinal cord.