目的　分析JAK STAT信号转导途径重要成员STAT3蛋白和该途径抑制蛋白SOCS 3在大鼠脊髓内的表达和细胞内定位分布。　方法　免疫细胞化学技术和形态计量学方法。　结果　STAT3免疫阳性产物主要分布于脊髓前角运动神经元的胞浆内 ;SOCS 3免疫阳性产物广泛分布于脊髓前角及后角神经元内、部分胶质细胞及神经纤维内。在前角运动神经元内 ,SOCS 3免疫阳性产物主要分布于核内 ,有时也可分布于胞浆中。　结论　STAT3和SOCS 3广泛表达于正常大鼠脊髓内 ,其中SOCS 3具有核蛋白或胞浆蛋白两种存在形式。 Objective To analyze the expression of STAT3 protein, an important member of JAK STAT signal transduction pathway, and the distribution of SOCS 3, an inhibitor of the pathway, in the spinal cord of rats. Methods Immunocytochemistry and morphometry methods. Results STAT3 immunoreactive products mainly distributed in the cytoplasm of motor neurons in the anterior horn of spinal cord. SOCS 3 immunopositive products were widely distributed in the anterior horn and posterior horn neurons, some glial cells and nerve fibers. In the anterior horn of motor neurons, SOCS 3 immunopositive products are mainly distributed in the nucleus, and sometimes also distributed in the cytoplasm. Conclusion STAT3 and SOCS 3 are widely expressed in the spinal cord of normal rats. SOCS 3 has two forms of nucleoprotein or cytoplasmic protein.