Semen, also known as Spermatozoa is a type of body fluid that is secreted by sexual organs of male reproductive system in order to fertilize female ova. In certain cases to analyze rape or sexual assaults, presumptive and confirmatory test of semen is performed.
Screening test is performed to analyze semen. Semen can be visualized using different lights with optimum wavelength filters. semen will fluorescence under those lights due to the present of choline and flavin conjugated proteins. Color can vary from blue to yellow.
Acid Phosphatase (AP) test is a presumptive test for the detecting the presence of acid phosphatase in seminal fluid/semen. AP is an enzyme that is present in larger quantities in semen than in any other body fluids. Seminal levels of AP can be usually observed within 10 seconds.
Microscopic examination of Semen is a confirmatory test. Semen is composed of sperm cells, epithelial cells, proteins, lipids and water. Sperm searches might turn negative due to oligospermic (low sperm count), Azoospermic (no mature sperm cells), Aspermic (no sperm cells in semen) conditions in the donor. Nuclear fast red dye stain stain the sperm head (nucleic acids) and Picro Indigocarmine stains the tails (proteins). epithelial cells stains as green/red color.
Y chromosomal PCR test or P30 is a confirmatory test for the presence of semen. PSA will bind to the mobile monoclonal antihuman P30 antibody attached to a dye.