Methods Immunohistochemistry SP technique was used to examine Ecd expression on epithelial cells of respiratory tract in smoking mice of different stages and dosages and the morphological changes observed by light and electron microscopy respectively.

• 方法应用免疫组织化学SP法，检测不同剂量、不同阶段吸烟小鼠呼吸道上皮细胞E?cd的表达，并在光镜及电镜下观察其形态学变化。