A Physical Method for Separating Spermatozoa from Epithelial Cells in Sexual Assault Evidence

    Volume 43, Issue 1 (January 1998)

    ISSN: 0022-1198

    CODEN: JFSOAD

    Published Online: 1 January 1998

    Page Count: 5


    Wolosin, D
    Office of the Chief Medical Examiner, New York, NY

    Baum, H
    Office of the Chief Medical Examiner, New York, NY

    Chen, J
    Associate Provost and Professor, John Jay College of Criminal Justice, New York, NY, and Graduate Center, City University of New York, New York, NY

    Kobilinsky, L
    Associate Provost and Professor, John Jay College of Criminal Justice, New York, NY, and Graduate Center, City University of New York, New York, NY

    Shaler, R
    Office of the Chief Medical Examiner, New York, NY

    (Received 7 March 1997; accepted 25 June 1997)

    Abstract

    The analysis of genetic markers for the purpose of individualization of semen specimens is extremely important in cases of sexual abuse and assault. The serological analysis of sexual assault evidence can sometimes be complicated because stains are often composed of a mixture of spermatozoa, vaginal epithelial cells and white and red blood cells. A filtration method has been developed to cleanly separate spermatozoa from epithelial cells based upon differences in size and shape. Nylon mesh filters of the appropriate pore size can be used to separate the smaller oval shaped spermatozoal cells from the larger and flatter epithelial cells. The former pass freely through the membrane while the latter are retained on the filter.

    In this study, cell separation was demonstrated by (a) microscopic observation of stained cells, (b) amplified fragment length polymorphism analysis of DNA obtained from separated cells. The results of these analyses indicate that: (1) Approximately 70% of spermatozoa in the mixed cell sample will penetrate the 10 µm pore size filter, (2) Only about 1–2% of intact epithelial cells will do so, and (3) A small number of nuclei from spontaneously lysed epithelial cells will cross the filter. Experimental results using mixtures of spermatozoa and vaginal epithelial cells prepared in different ratios support the conclusion that the filtration process is an efficient and reliable method to separate spermatozoa from epithelial cells in casework specimens for subsequent DNA analysis.


    Paper ID: JFS16097J

    DOI: 10.1520/JFS16097J

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    Title A Physical Method for Separating Spermatozoa from Epithelial Cells in Sexual Assault Evidence
    Symposium , 0000-00-00
    Committee E30