Barr Bodies

What sample is needed for Barr Bodies?

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

What are the indications for Barr Bodies?

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

What are the precautions for the Barr body sample?

1. Don’t take the sample during the first week of a newborn’s life.
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 Barr chromosome bodies.
4. 40% to 60% of the cells show identifiable Barr bodies.

How will you define the 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. The Barr body that appears for each X-chromosome.
3. Therefore, XX females will exhibit one Barr body, while males with XY chromosomes will display no Barr body.
4. Therefore, if there are XXY, it will display two Barr bodies.

 Discuss the history of the Barr Bodies?

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

What is the 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, specifically the X chromosome, is inactivated.
3. Sometimes, one of the inactivated X chromosomes is donated by the father.
4. The mother contributes to the other (X).
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.
7. Denver classification, total chromosomes are 46 in number:
   1. 22 pairs.
   2. One pair shows XX, indicating that it is female.
   3. Other pairs may show XY, indicating male.
8. Therefore, the female XX chromosome has one Barr body and is considered chromatin-positive.

9. While males have XY, so no Barr body, and are considered chromatin negative.

How will you perform the 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 with 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.

Questions and answers: