An easy and accurate technique was devised for electron microscopical observation of the selected region in a wide tissue area. Serial one micron Epon sections were obtained by use of an ultra-microtome, stained with toluidine blue, and placed on a glass microscope slide. A small wire-loop was used for picking up and transferring of sections. A selected section of the serial sections was freed from the slide and mounted on the facet of another prepared Epon block. By warming the section-mounted block in an oven, the section was let stick fast to the block surface. The most important portion of the mounted section was ultrathin-sectioned in the ordinary way for electron microscopy. As for the thickness of initial serial sections, one micron was most suitable for light microscopy and ultrathin-sectioning.