Where an arbitrary point on an image is designated in the field of a medical image, it is generally designated on a sectional image, and an arbitrary point on a three-dimensional image cannot be designated. A reflective surface of the optical waveguide has first and second reflective surfaces intersecting at a predetermined boundary line, and a light-emitting surface of the optical waveguide has first and second regions divided by the predetermined boundary line. The invention further relates to vector systems useful for modifying the genomes of eukaryotic cells to alter the expression of endogenous genes. The memory device includes a plurality of memory device memory locations. The strip to be torn out includes a pulling means having a sufficient tearing resistance for preventing a separation between the pulling means and the strip to be torn out during a tearing operation.