Chen J, Kobilinsky L, Wolosin D, Shaler R, Baum H
John Jay College of Criminal Justice, New York, NY, USA.
J Forensic Sci. 1998 Jan;43(1):114-8.
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 microns 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.
在性虐待和性侵犯案件中，为实现精液样本个体化而对遗传标记进行分析极为重要。性侵犯证据的血清学分析有时会很复杂，因为污渍通常由精子、阴道上皮细胞以及白细胞和红细胞的混合物组成。已开发出一种过滤方法，可根据大小和形状差异将精子与上皮细胞干净地分离。适当孔径的尼龙网过滤器可用于将较小的椭圆形精子细胞与较大且较扁平的上皮细胞分离。前者可自由穿过膜，而后者则保留在过滤器上。在本研究中，通过以下方式证明了细胞分离：(a) 对染色细胞进行显微镜观察，(b) 对从分离细胞中获得的DNA进行扩增片段长度多态性分析。这些分析结果表明：(1) 混合细胞样本中约70%的精子会穿透10微米孔径的过滤器，(2) 只有约1 - 2%的完整上皮细胞会这样做，(3) 少量自发裂解的上皮细胞核会穿过过滤器。使用不同比例制备的精子和阴道上皮细胞混合物进行的实验结果支持了以下结论：过滤过程是一种高效且可靠的方法，可在实际案件样本中从上皮细胞中分离精子，以便后续进行DNA分析。
