SEMEN ON PANTIES - HISTORY OF SEMEN DETECTIONS

Microscopic Examination for Sperm

There are numerous extraneous objects which are so like the detached heads and tails of spermatozoa as to mislead even those who are thoroughly experienced in the work.  The generally accepted rule is that no body which simply resembles the head or tail should be considered as serious proof and the search must continue until perfectly formed and entire spermatozoa are recognized. 

  • Microscopic Examination Of Stained Slides For Spermatozoa (Reference 11)
    • Equipment
      • Microscope (with approximately 200X – 400X total magnification, with or without phase capability)
    • Materials
      • Distilled water, xylene substitute, or other appropriate mounting medium
      • Coverslips
    • Procedure
      • Quickly scan at approximately 200X total magnification. Confirm at approximately 400X total magnification.
        • With phase microscopy: Spermatozoa heads are neon-like pink/red with darker pink/purple acrosomal caps and green tails. Epithelial cells and most bacteria stain green with some of the nuclei pink/red; however, these are shaped differently than spermatozoa. Yeast cells take on the same color as spermatozoa, but are shaped differently.
        • Without phase microscopy: Spermatozoa heads are neon-like pink/red with pale pink (almost colorless) acrosomal caps, blue-green necks/midpieces, and green tails. Epithelial cells appear bright blue with red to purple nuclei.
      • Document the approximate number of spermatozoa and spermatozoa heads on the smear per hpf (approximately 400X total magnification), per lpf (approximately 200X total magnification), per length of slide, or per slide, as appropriate. 
      • Place all smears submitted in the PERK back into the PERK. Properly label and return all other spermatozoa positive smears with the evidence.

       

  • Microscopic Examination Of Unstained Slides For Spermatozoa (Reference 11)
    • Unstained smears may be examined using phase contrast microscopy.
    • Equipment
    • Microscope (approximately 200X – 400X total magnification) with phase capability
    • Materials
      • Microscope slides
      • Coverslips
      • Applicator sticks
    • Reagents
      • Distilled water
    • Procedure
    • Place a small amount of an extract of a suspected semen stain on a microscope slide and cover with a coverslip, or add a drop of distilled water to a smear from the PERK, use an applicator stick to mix the water and the material on the smear, and cover with a coverslip.
      • Scan quickly with phase at approximately 200X total magnification. Confirm with phase at approximately 400X total magnification.
      • When the coverslip is touched gently, the spermatozoa and/or spermatozoa heads will roll, exhibiting their characteristic 3-dimensional shape. Use the distinctive size and morphology to identify the spermatozoa/spermatozoa heads.
      • Document the approximate number of spermatozoa and spermatozoa heads on the smear per hpf (approximately 400X total magnification), per lpf (approximately 200X total magnification), per length of slide, or per slide, as appropriate.
      • Place all smears submitted in the PERK back into the PERK. Properly label and return all other spermatozoa positive smears.