Examination of seminal fluid is important on many accounts.
CIVIL importances —
1. Compensation on the ground of acquired sterility
2. Disputed paternity
4. Artificial insemination
5. Compensation on the ground of failure of vasectomy cases, leading to pregnancy of the wife.
6. Divorce cases – non-ejaculation amounts to impotence.
CRIMINAL importances –
In relation to sex offence cases
a) Concerning commission of sex offence.
b) Identification of the offender.
EXAMINATION OF SEMINAL FLUID :
Physical appearance —
When fresh and collected in a glass container, seminal fluid is pale-white or greyish white, thick, viscid fluid having a characteristic smell. On standing, the fluid loses viscidity and becomes thin.
When dried on cloth, the area appears slightly glistening, starchy hard in feeling, irregular in shape and distribution, and is whitish on dark clothes, and has fluorescence property when examined under ultraviolet light in a dark room.
Quantity in each ejaculation is about 4-5 ml. after a period of abstinence.
Chemistry of seminal fluid – Seminal fluid is alkaline.
The following chemicals are present in spermatozoa and seminal plasma:
In SPERMATOZOA —
4. Other enzymes.
In seminal PLASMA —
3. Citric add
7. Phosphatases, proteases and other enzymes.
Chemical tests —
1. FLORENCE test:
This is the test for presence of choline in the stain extract. The stain extract is dried on a glass slide, covered with a cover slip and a drop of potassium tri-iodide solution or a solution of 1.65 gm. KI + 2.54 gm. Iodine in 30 ml. of distilled water is added by the side of the cover slip. Dark brown rhomboid crystals of choline periodide appear very soon which are seen under the microscope, whose sizes are larger than haemin crystals.
2. BARBARIO’S test:
The dried stain extract on the glass slide is covered with a cover slip and through the side of the cover slip a drop of saturated aqueous or alcoholic solution of picric acid is added to get yellowish, long, needle shaped spermin picrate crystals which appear very rapidly and tells about the presence of spermin in the stain extract.
3. ACID PHOSPHATASE test:
Acid phosphatase is present in almost all body fluids. But its concentration in seminal fluid is maximum (about 20 to 400 times more than normal of about 20 units present in other body fluids).
The stained area is moistened and soaked with a blotting paper. The blotting paper is sprayed or treated with alpha-naphthylphosphate and fast black K dye. A purple colour appears if there is acid phosphatase. Acid phosphatase of semen origin gives the positive reaction very rapidly (within 1/2 minute) in comparison with acid phosphatase of other origin.
4. CREATINE PHOSPHOKINASE:
It is also present in seminal fluid in a very high concentration.
5. AMMONIUM MOLYBDATE gives yellowish co-louration when added to seminal stain extract.
All the chemical tests are screening tests because, many other body fluids also give positive reaction for these tests. However if these tests are negative then presence of seminal fluid in the stain is excluded. Rapidly positive acid phosphatase test is a more dependable one.
GEL ELECTROPHORESIS TEST however gives almost diagnostic result for presence or absence of seminal fluid.
In any case, the conclusive test for semen is demonstration of SPERMATOZOA with the help of a microscope. Human spermatozoa are about 55µ to 70µ in length with slender long tail and a heart-shaped head of the dimensions of about 5µ length and 3.5µ maximum breadth. The number of spermatozoa present per ml. of seminal fluid, in the average, is between 60 to 150 million.