Seminal stains.

Seminal stains.


Introduction.

  • Sensabaugh in 1977 reported the event of isolation of p30 in human seminal  fluid.  It is a glycoprotein of prostate origin.
  • Detection  of seminal  stains  becomes  important  in cases  of  rape, attempted  rape, sexual  murders of  female, kidnapping, sodomy, bestiality, adultery  and  indecent  assault  etc.
  • Seminal  stains  are  generally found  on  the  clothing, but  may be present  on  the  body  of  the  victim  or  accused,  on  the  bed  clothes,  site of offence,  seat  of motor car; on the  floor  or on  the grass.
  • Normal semen reference pH range is 7.2 to 7.8. Variations in volume and low pH may be  due to congenital abnormalities of the genital tract or to obstruction.

Tests  to  detect  semen are  :

A) Chemical  tests  :These tests  are  divided  into  :

1) Microchemical  tests  :

Florence  test:

  1. This test was discovered by Dr.Florence in the year 1886.
  2. When Florence reagent (PotassiumIodide+Iodine+Water) is applied to the slide it produces rhomboidal shape  dark crystals of choline periodide.
  3. choline can be detected if swab is collected within one day of sexual act,

Barberio’s  test:

  1. Invented by Barberio in the year 1905.
  2.  When the questioned stain is  allowed to react with picric acid it leads to the formation of yellow needle shaped  spermine picrate crystals.

2) Enzyme tests: Since spermatozoa contain gram positive protein, the  presence of spermatozoa will be confirmed by microscopic appearance of purple bodies

Acid phosphatase & specific glycoproteins:

  1. This test is adopted because of high acid  phosphatase activity of semen.
  2. Stability of  acid phosphatase activity in seminal stain depends on temperature

3) Ammonium  molybdate  test:  lt  gives  deep  yellow  colour, due to  presence  of phosphorus. 

B)  Microscopic examination : It  is  done  to  demonstrate the  presence of  spermatozoa in  the  vaginal fluid  or in  stain. 

C)  Biological  examination:

  • Precipitin  test  :  To  know  the  species  to  which  semen  belongs.
  • Blood  group  can  be  known  from  semen

D)  UV light:

  • Invisible,  softened  and dry  semen  stains of the  clothes can  be  rendered  distinct  by  the  filtered UV light which  produces  bluish  fluorescence.
  • A mercury lamp inside of the unit produces a high intensity of UV (320-400nm) and visible light (400-700 nm) which was developed  to detect biological stains even in daylight.

E) Testes  for  determination  of  specific protein  component (e.g. LDH  isoenzyme):

  • These are  immunoelectrophoresis,  gel  diffusion  precipitation, gel  electrophoresis,  immunodiffusion,  isoelectric focusing  and TLC (thin  layer  chromatography).

Exam Important

A) Chemical  tests  :These tests  are  divided  into  :

1) Microchemical  tests  :

Florence  test:

  1. This test was discovered by Dr.Florence in the year 1886.
  2. When Florence reagent (PotassiumIodide+Iodine+Water) is applied to the slide it produces rhomboidal shape  dark crystals of choline periodide.
  3. choline can be detected if swab is collected within one day of sexual act,

Barberio’s  test:

  1. Invented by Barberio in the year 1905.
  2.  When the questioned stain is  allowed to react with picric acid it leads to the formation of yellow needle shaped  spermine picrate crystals.

2) Enzyme tests: Since spermatozoa contain gram positive protein, the  presence of spermatozoa will be confirmed by microscopic appearance of purple bodies

Acid phosphatase & specific glycoproteins:

  1. This test is adopted because of high acid  phosphatase activity of semen.
  2. Stability of  acid phosphatase activity in seminal stain depends on temperature

3) Ammonium  molybdate  test:  lt  gives  deep  yellow  colour, due to  presence  of phosphorus. 

B)  Microscopic examination : It  is  done  to  demonstrate the  presence of  spermatozoa in  the  vaginal fluid  or in  stain. 

C)  Biological  examination:

  • Precipitin  test  :  To  know  the  species  to  which  semen  belongs.
  • Blood  group  can  be  known  from  semen

D)  UV light:

  • Invisible,  softened  and dry  semen  stains of the  clothes can  be  rendered  distinct  by  the  filtered UV light which  produces  bluish  fluorescence.

 

Don’t Forget to Solve all the previous Year Question asked on Seminal stains.

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