Semen, persistence of spermatozoa and very subjective microscopic examination

Question 1

why do we need to know thiss

Answer 1

highly variable
victims postcoital activity can cause vaginal drainage
menstruation can affect persistence
depends on location of deposit
gives us a timeline or can corroborate a story or report
the longer the time between collection at, decrease the concentration and ultimately the likelihood of finding evidence

Question 2

persistence of spermatozoa

Answer 2

motile sperm in living subjects
reach uterine tubes 30-60 minutes after copulation
6-8 house in vagina with tails
after no tails
5-6 days in cervix
post mortem subject
sperm identified in vagina 16 days 34 days and 3-4 months with tails after death
persistence significantly affected by environmental condition

Question 3

female reproductive system areas

Answer 3

external
vaginal
cervical

Question 4

vaginal persistence

Answer 4

expected in sample taken within 8 hours of assault
reasonable chance up to 24 hours
possible from 48 hours up to 6 days (rare) after
studies have shown that there is a 54-58% chance of sperm recovery within the first 24 hours of deposition
vag cavity high ph and hostile environment for sperm
sperm is around 7.5

Question 5

cervical persistence

Answer 5

longer than vaginal peristence
sperm reach the cervix immediately after ejaculation and can remain for 5-6 days
more favorable ph than vagina (vag is highly acidic)
cervix is more neutral sperm is 7.5
nooks and crannies spaces to hide

Question 6

anal/rectal persistence

Answer 6

up to 20 hours post deposit
feces is mostly bacteria so bad environment for sperm cells
anal is outside
rectal is inside
sodomy is an additional charge
must corroborate
lack of sperm does not mean lack of sodomy

Question 7

oral persistence

Answer 7

up to 6 house post deposition of semen
other report suggest 2-3 hours post ejaculation
saliva 1-1.5L saliva a day
lots of liquid in mouth
brush teeth, rinse mouth

Question 8

oral sample collection

Answer 8

use of dental floss as a method of sampling the oral cavity for spermatozoa may extend the recovery period
good idea if you collect with floss and also swab

Question 9

persistence in a deceased victim

Answer 9

sperm have been shown to be present in postmortem vagina up to 16 days after death
no drainage
one study found intact sperm with tails 34 days postmortem
dealing with decomposition of the body, therefore if less decomposed ie In color temps more likely to find sperm
heat and humidity play a major role in decomposition rate
give more time, look at all samples of deceased, unconscious, unaware children, etc

Question 10

summary

Answer 10

1. cervical 5-6 days, expect longest
2. vaginal up to 6 days
3. anal 20 hours
4. rectal 20 hours
5. oral 2-3 up to 6 hours
   deceased, 16 days

Question 11

vaginal epithelium

Answer 11

similar to buccal cells
intermixed with sperm cells
neutrophils WBCs

Question 12

oral epithelium

Answer 12

can be intermixed with streptococci in oral samples or buccal
neutrophil WBCs

Question 13

glycjogenated cells
vaginal only (mostly)

Answer 13

vaginal epithelial cells accumulate glycogen under the influence of circulation estrogens
lactobacillus acidophilus
predominate bacteria because of the ability to metabolize glycogen and lactic acid
acidic ph prevents establishment of most bacteria and the potentially pathogenic yeast, Candida albicans

Question 14

lugol’s iodine stain

Answer 14

vaginal cells
at least 10% glycjogenated, average > 25%
oral cells
<1% glycogenated
highest reported value of 9% by PAS method
rectal cells
50% glycogenated
penile urethral cells many contain glycogen

Question 15

periodic acid schiff (PAS) stain

Answer 15

similar results to lugol
shows a higher % of glycogen-positive cells

Question 16

dane’s stain

Answer 16

histological technique for distinguishing between epithelial cells in forensic case work
methanol fixation
coupled with the dane’s staining method
specific to keratin was the only technique that distinguished between all three cel types