The development of electronic medical archives requests to mosaic the medical microscopic images to a whole one, and
the stitching result is usually a massive file hard to be stored or accessed. The paper proposes a file format named
Medical TIFF to organize the massive microscopic image data. The Medical TIFF organizes the massive image data in
tiles, appends the thumbnail of the result image at the end of the file, and offers the way to add medical information into
the image file. Then the paper designs a three-layer system to access the file: the Physical Layer gathers the Medical
TIFF components dispersed over the file and organizes them hierarchically, the Logical Layer uses a two dimensional
dynamic array to deal with the tiles, and the Application Layer provides the interfaces for the applications developed on
the basis of the system.