The Digital Cytocochleogram P.A. Santi a, * , A. Blair a , B.A. Bohne b , J. Lukkes a , J. Nietfeld a a Department of Otolaryngology, University of Minnesota, Rm. 121, Lions Res. Build., 2001 Sixth St. SE, Minneapolis, MN 55455, USA b Department of Otolaryngology, Washington University School of Medicine, Box 8115, 660 South Euclid Ave., Saint Louis, MO 63110, USA Received 15 September 2003; accepted 29 January 2004 Available online 18 March 2004 Abstract The Mouse Cochlea Database (MCD) is a collection of resources that include digital images and bibliographic information on the mouse cochlea and is available at: http://mousecochlea.ccgb.umn.edu. The purpose of this communication is to report on the development of one MCD resource: the Digital Cytocochleogram. A cytocochleogram is a graphic representation of the anatomical state of the hair cells along the complete width and length of the organ of Corti. The Digital Cytocochleogram provides Internet users with a complete collection of digital images of one or more surface preparations of the mouse organ of Corti from which morphometric information can be obtained. By moving a mouse driven, screen cursor over a digital image, the location and ap- proximate frequency region of the anatomical structure is displayed. Users can also measure the straight-line distance between any two structures on the image. The Digital Cytocochleogram resource uses two software programs, the Coordinate Finder and Viewer, which are written as CGI scripts. The Coordinate Finder program maps each digital image to an X ,Y coordinate system. The total length of the organ of Corti from all tissue segments is computed using an arc-distance approximation formula, with the lateral border of the inner pillar cell headplates serving as a trace line or reference location. After all of the digital images of the tissue segments are mapped, they are placed on the MCD Website where users can use the Viewer program to view and morphometrically assess structures using a web browser. A single, complete surface preparation from a normal mouse is presently available on the MCD website. As the MCD grows, additional images of surface preparations at different magnifications from normal, mutant, and experimentally altered mouse cochleas will become available. Ó 2004 Elsevier B.V. All rights reserved. 1. Introduction In 1966, Engstrom and coworkers described a meth- od for producing surface preparations of the organ of Corti and a 2-dimensional graphic representation of damaged hair cells along the length of the basilar membrane. This graphic record was called a cochleo- gram or cytocochleogram. Its purpose was to relate hair-cell damage with frequency specific changes in hearing thresholds following acoustic trauma or oto- toxic drug exposure. Subsequently, a variety of methods have been used to produce surface preparations of the organ of Corti and to represent structural damage in the form of a cyto- cochleogram. Whole-mount, surface preparations of the organ of Corti/basilar membrane complex are usually prepared from chemically fixed tissues. Decalcified, dissected tissues can be mounted on a slide in aqueous media (Engstrom et al., 1966; Santi and Muchow, 1979), from undecalcified, plastic-embedded tissues (Bohne, 1972; Santi, 1986), or from Scanning Electron Micro- scopic preparations (Hunter-Duvar, 1978). However, plastic-embedded tissues offer the best advantages of tissue morphology and preservation of structural details. An important factor for producing surface preparations is that all of the organ of Corti with the corresponding hair cells must be harvested in order to relate structural damage with the frequency/distance map of the basilar membrane. Engstrom et al. (1966) represented the four rows of hair cells as open (i.e., normal cells) and filled (i.e., damaged cells) circles. Other investigators have * Corresponding author. Fax: +612-626-9871. E-mail address: p.santi@amn.edu (P.A. Santi). Abbreviations: CGI, common gateway interface; MCD, mouse cochlea database; NIDCD, national institute on deafness and other communication disorders; PHP, hypertext preprocessor 0378-5955/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.heares.2004.01.017 Hearing Research 192 (2004) 75–82 www.elsevier.com/locate/heares