Abstract: The present invention aims to develop a method for specimen preparation, which ensures the maintenance of both tissue morphology and nucleic acid quality (particularly RNA quality). The present invention further aims to prepare a specimen by this method, from which desired cells are then collected by microdissection and analyzed for gene expression. A method for specimen preparation from various frozen or unfrozen organs or tissues (excluding hard tissues) of the whole body, which comprises the following steps: 1) fixing a target organ or tissue with PFA fixative; and 2) embedding the same in paraffin by the AMeX method.