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Development of an Automated System to Detect Spermatozoa on Laboratory Slides to Increase Productivity in the Analysis of Sexual Assault Cases

NCJ Number
Date Published
November 2011
60 pages
This project's goal was to develop an automated system for the detection of spermatozoa on laboratory slides, so as to increase productivity in the processing of evidence in sexual assault cases.
With new components introduced by this project, the scanning time for spermatozoa on laboratory slides improved from 2 hours to an average time of 20 minutes. A routine case that involves three slides can often be completed within 1 hour. This allows the analyst to forward results to the DNA section and the investigator within a shorter time period. The project's initial approach was to use a bright field microscope produced by one company. The project soon expanded to compare two bright field microscopes produced by two companies in order to determine which system worked better. Also tested was the possibility of using florescent dyes or fluorescently tagged antibodies specific to human sperm cells for viewing with a fluorescent microscope. The goal of the fluorescence aspects was to provide a fast screen of potential sperm cells under fluorescence and with the ability to then switch to bright field in order to identify the sperm (i.e., a double-stain approach). Both automated microscopy systems purchased included a microscope, a stage that held multiple slides, a computer system to process the images, and a screen for viewing the gallery of images collected. The systems were capable of scanning using bright field or fluorescence. The automated bright field microscopes identify the sperm by using a camera to capture the images of each object seen on the slide. The computer processes these images and judges by the size, shape, and color whether or not the object is a sperm cell. The slides are stained with a stain referred to as the Christmas Tree stain, since it colors the sperm red and green. 12 figures, 1 table, and 6 references

Date Published: November 1, 2011