1. Forensic Biology by Richard Li
Chapter 8: Identification of Semen
Forensic Biology by Richard Li

2. Biological Characteristics
Typical ejaculation
2-5 ml of semen
Seminal fluid
Seminal vesicle fluid- 60% of ejaculate
Prostatic fluid secretions- 30% of ejaculate
Acid Phospahatase (AP) & Prostate Specific Antigen (PSA)
Epididymis and bulbourethral glands- each 5%
Sperm cells- Spermatozoa
Forensic Biology by Richard Li

3. Biological Characteristics
Vasectomy- block spermatozoa
Still produces ejaculate with seminal vesicle fluid and prostatic fluid
Oligospermia- low sperm count
Aspermia- no sperm
Forensic Biology by Richard Li

4. Spermatozoa Three distinct regions: Head Middle Piece Tail
Forensic Biology by Richard Li

5. Acid Phosphatase Optimal activity in acidic pH environment
Present in lysosomes
Prostate AP
Half-life at 37 degrees C: 6 months
Forensic Biology by Richard Li

6. Prostate-Specific Antigen
Major protein in seminal fluid
Also detected in urine, fecal matter, sweat, milk
Half-life of dried stain: 3 years
Forensic Biology by Richard Li

7. Seminal Vesicle Specific Antigen
Semenogelins
I & II
Higher concentration in seminal fluid than PSA
Not found in urine, milk, sweat
Forensic Biology by Richard Li

8. Lighting Techniques Locating dried stains UV light Argon laser
Alternate light source (ALS) nm
Forensic Biology by Richard Li

9. Colorimetric Assay
AP catalyzes the removal of the phosphate group from a substrate
Positive= purple color
Forensic Biology by Richard Li

10. Fluororimetric Assay More sensitive than colorimetric
AP catalyzes the removal of the phosphate residue on the substrate 4-methylumbelliferone phosphate which generates fluorescence under UV light
Forensic Biology by Richard Li

11. Confirmatory Tests Microscopic examination Christmas Tree Stain
Laser capture microdissection
Identification of prostate-specific antigen
Radial immunodiffusion
Rocket immunoelectrophoresis
CIE
ELISA
Imunnochromatographic assays
Most sensitive
Forensic Biology by Richard Li