Identification of Semen

semen is important in

sexual assault cases and is a alrge percentage of forensic casework

semen is comprised of

spermatozoa and seminal fluid

what is the confirmation of the presence of semen

spernatazoa

what is the secretions from seminal glands

seminal fluid

spermatozoa is about

10-25% of semen composition

spermatozoa is formed in the

testes

spermatozoa is transported and stored in the

epididymis where they undergo functional maturation

spermatozoa are transferred through the

vans deferens to the ejaculatory duct into the urethra 

once spermatozoa reaches the urethra, they are joined with

secretions from the prostate

the head of a sperm cell contains

nucleus with densely packed chromosomes

the mid-piece of the sperm is a

short neck containing mitochondria that provides energy for moving tail

the sperm tail offers

sperm motility

accessory gland secretions (75-90%) are from the 

prostate (30%) and seminal vesicles (60%)

the prostate produces

high concentrations of acid phosphatase and prostate specific antigen (PSA) used in forensic testing

the seminal vesicles secrete proteins that

play a role in the coagulation of the ejaculate, also contains flavins

what causes semen to fluorescence?

flavin proteins

typical ejaculation amount is

1-6 mL (average 3 mL)

what does the volume of ejaculate depend on?

• time from previous ejaculate

• metabolic activity of glands 

• partial ductal obstruction and retrograde ejaculation

normospermia makes up about

50-150 million/mL (average is 100 million/mL)

aspermia means

no sperm

oligospermia is also called

aspermia

oligospermia/aspermia can be caused by

• illness

• nutritional deficiency

• therapeutic drug use

chronic cases due to 

• congenital deformities

• chemotherapeutic drugs

• exposure to industrial chemicals

• vasectomy

how many vasectomies fail

1-2%

what is a polyamine in the presumptive test

• spermine - barberio crystal test

• choline - florence crystal test

what enzymes are used in presumptive screening tests

seminal acid phosphatase (SAP)

where is spermine synthesized

in the prostate

what is the barberio test

spermine phosphate crystals formed by reaction of spermine with anions (phosphate or picrate)

spermine enhances

sperm motility

where is phosphorycholine (PC) synthesized

in the seminal vesciles

how is choline formed

by hydrolysis of PC by SAP

what is the most common screening test

seminal acid phosphatase presumptive test

SAP enzyme cleaves a variety of organic phosphates such as

phenyl-

p-nitrophenyl

a-naphhyl

thymolpthalien-

elevated levels of SAP in the blood is indicative of

prostate cancer

seminal acid phosphatase is how much greater than any other body fluid

100-1000 fold

phenyl phosphate

p-nitrophenyl phosphate 

a-naphthyl phosphate

thymolphthalien monophosphate

seminal acid phosphatase comes from glands that are not

affected by vasectomies

seminal acid phosphatase is active at what pH

acidic

prostate specific antigen is not a

confirmatory test

prostate specific antigen is a major protein in

seminal fluid

prostate specific antigen nis responsible for hydrolyzing

semenogelin

prostate specific antigen creates a

gel matrix around ejaculated sperm

prostate specific antigen is an important clinical indicator of

malignancy

prostate specific antigen is present in

urine and peripheral blood

P30 identification methods consist of

crossover electrophoresis

ouchterlony double diffusion

immunochromatography

ELISA

p30 ELISA uses what type of ‘sandwich’

antibody-antigen-antibody (ab-ag-ab)

normal semen contains up to

96% abnormal forms of sperm, 1-2% immature forms

immature germinal cells, leucocytes, epithelial cells can all be used in

DNA recovery

abnormal sperm have

• multiple heads

• single head, multiple tails

• cytoplasmic droplets

sperm can be visualized using what stains

• nuclear fast (NF), red/picroindigocarmine solution (PICS)

• hematoxylin/eosin (H&E)

what animals have sperm that is hard to distinguish from humans

• rabbit

• boar

• ram

• bull

• other primates

mouse and rat sperm has a

hook shaped head

SAP is available for

12-48 hours

p30 is available for

1-3 days

sperm is available for

3-5 days

ability to test sperm on post-coital individuals is

dependent on the environmental conditions

semen can be lost from the vaginal environment due to

• drainage

• dilution with vaginal fluid

• phagocytosis of spermatozoa by neutrophilic lymphocytes and mononuclear cells

vaginal swabs can be collected up to

120 hours (5 days)

anal swabs can be collected up to

72 hours (3 days)

oral swabs can be collecetd up to

24 hours (1 day)

bite marks and saliva on skin can be collected up to

96 hours (4 days)