Lamellar bodies, tubular and lattice myelin figures (TMF and LMF)of the Type Ⅱ epithelial cells lavaging from the lungs of adult male rats following injection of a single dose of 10mg of active carbon powder, silica dust, uranium ore dust and U_3O_8 powder were observed by scanning and transmisson electron microscope as well as freeze-etching technique. According to the membrane split theory and our observations, we suggested that the lamellar bodies were composed of a lot of subunits, the square crystalls. These crystals linked up each other to form a cuboidal structure and arranged regularly into ring-like lamellae. A central core was surrounded by the lamellae to constitute a lamellar body, which can be distingushed into three types, namely the wollen ball-shaped, the circular concentric shaped and the lattice-shaped. When the circular concentric lamellar bodies were dissociated from the type Ⅱ epithelial cells, they then extended to form the pulmonary surfactant system (LMF). The amount of the pulmonary surfactant system substances in the rats administrated the above-mentioned foreign substances was obviously higher than that of controls.