Phase contrast microscopy versus differential interference contrast microscopy as applicable to the observation of spermatozoa.

A review of available literature has shown something of a paucity of suggested and applied microscopic techniques on the identification of human spermatozoa in forensic casework. Phase contrast microscopy (PC) has been mentioned as the desirable technique by Kirk [1] and Kivela [2]. The advantages of PC as compared with bright-field are well known and would most certainly include simplifring the task of locating any spermatozoa present. Some other advantages are an apparent improvement in the morphological detail presented to the observer and some reduction in the fatigue associated with the eyestrain accompanying this frequently tedious task. The purpose of this study was to evaluate the potential of incident light differential interference contrast (DIC) microscopy for the identification of human spermatozoa. Also, DIC was compared with PC in order to establish the pros and cons of each technique as applied to such examinations. The chosen criteria for these comparisons were (1) what microscopic details of the cell's structure were visible, (2) the quality of the observed image in terms of sharpness and freedom from interference by non-sperm cell particulate matter invariably present in forensic casework, and (3) the ability to work with substrates other than microscope slides.