Barr Bodies

Sample for Barr Bodies

1. Scrapings from buccal mucosa or the vaginal wall in some women.
2. The buccal mucosa is scrapped and smears the slide. It is fixed immediately. Make a monolayer of the cells.
3. While the Drumstick is done on the white cells (WBC) to see the presence of the drumstick.
4. The more specific method is a nucleic acid probe, which is more sensitive than Barr bodies.

Indications for Barr Bodies

1. This is an easy and cheapest test.
2. This screening test is for ambiguous genitalia (where the sex characters are unclear).
3. It may be done for the delayed onset of puberty.
4. This test may be done for Turner and Klinefelter syndromes.

Precautions for barr body sample

1. Don’t take the sample during the first week of the life of newborns.
2. Don’t take samples during the adrenocorticosteroids or estrogen therapy. This will lead to a decrease in the number of Barr bodies.
3. Inadequate preparation may obscure the chromosome Barr bodies.
4. 40% to 60% of the cells show identifiable Barr bodies.

Definition of Barr Bodies:

1. Barr bodies or nuclear sexing is where buccal or vaginal smears are stained with cresyl violet and examined microscopically.
   1. A dense barr body on the nuclear membrane represents one of the X-chromosomes, occurring in 30% to 60% of females.
   2. Barr bodies are stainable structures.
2. Barr bodies are present in the nucleus, and there are stainable sex chromosomes. Barr body that appears for each X-chromosome.
3. So XX females will show one bar body, while the male has XY chromosome will show no barr body.
4. So if there are XXY, it will show two barr bodies.

History of the Barr Bodies:

1. The barr bodies are named after the discoverer  Murray Barr and Bertram in late 1940.
2. This is also called sex chromatin.
3. Inactivated X chromosome is observable in many interphase cells as highly condensed intranuclear chromatin bodies are Barr bodies.
4. The barr body is the inactive X chromosome in the female somatic cells.
5. This is basically a compact structure of the chromatin in the nuclei in the female.
6. Barr body is the condensed chromatin, dark staining spot at the periphery of the nucleus of each somatic cell in the human body.

Mechanism of Barr Bodies Formation:

1. This inactivation occurs very early in embryonic development, approximately 7 to 14 days after fertilization.
2. One of the chromosomes, XX, one of those is inactivated.
3. Sometimes one of the inactivated X chromosomes is donated by the father.
4. In other is contributed by the mother.
5. This cell with an inactivated X chromosome gives the descendant the same structure.

6. This helps determine sex where the infants’ physical features are unclear.
   1. Denver classification, toat chromosomes are 46 in number:
      1. 22 pairs.
      2. One pair shows XX, indicating female.
      3. Other pairs may show XY, indicating male.
7. So the female XX chromosome has one bar body and is considered chromatin positive.

Barr’s body positive indicates female.

8. While male has XY, so no barr body and considered chromatin negative.

Barr’s body negative indicates Male.

Procedure for Barr bodies:

1. Take epithelial cells from the buccal mucosa or vaginal smear.
   1. Make a monolayer cell slide.
2. Fix these cells by the fixative.
3. Stain with cresyl violet.
4. Examine under the microscope.
5. There is a dense body (Barr body) on the nuclear membrane; it represents one of the X-chromosomes.
6. This will be seen in 30% to 60% of the female somatic cells (other than the reproductive cells).

Drumstick in the neutrophils:

1. The drumstick is the drum-shaped nuclear appendage seen in 2% to 3% of the neutrophils in females, indicating 2 X chromosomes. This can be confirmed by karyotyping.
2. It is not found in males.
3. There is a lower incidence of the drum-stick in Klinefelter syndrome (XXY) as opposed to the extra barr body.
4. Double drum-stick are exceedingly rare and have no diagnostic value.

Normal Barr Body

• Male = No barr bodies are seen.
• Female = Barr’s body is positive.

Normal Drumstick

1. Drumstick positive in females (2% to 3% of polys) indicates the presence of two X chromosomes.
2. Drumstick negative in males.
3. If <10% of cells contain the Barr Bodies in patients with female sex organs, chromosomal karyotyping is recommended to find any abnormality.

Interpretations of Barr Body (Drumstick)

1. This barr body test is advised to screen ambiguous or doubtful sex characters.

Turner’s syndrome

1. Female (XO) will have no barr body.
2. This is a chromosomal sexual abnormality in females.
3. These patients have one chromosome deletion showing only 45 chromosomes instead of 46.
4. There is a deficiency of secondary sexual features and small genitalia.
5. There may be a webbing of the neck, coarctation of the aorta, and short fingers.
6. They don’t mensurate and usually lack ovaries.
7. Buccal smear for Barr bodies will be negative.
8. If Barr’s body is positive, then advise chromosomal karyotyping because sometimes these patients have 50% positive and 50% negative cells for Barr’s bodies.

Klinefelter syndrome

1. A male with (XXXY) will have a barr body.
2. The person looks like a male, but the chromosomes show XXY or XXXY.
3. Ther external genitalia is normal except for small testes.
4. There are decreased body hairs, and may be gynaecomastia.
5. There is a mental deficiency, but they may have normal intelligence.
6. Mostly these patients are sterile.
7. The biopsy will confirm the diagnosis, showing atrophic semniferous tubules.
8. Chromosomal karyotyping is the method of choice.

Barr bodies pattern in females and Klinefelter syndrome

9. Females with XXX chromosomes will have two barr bodies.
10. The female cell with four X chromosomes has three barr bodies.

NOTE
If needed, the result should be confirmed by chromosomal karyotyping.

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