The main difference between the drumstick and Barr body is that the drumstick is a drumstick-like projection coming out from the white blood cells’ nucleus, whereas the Barr body is the condensation at the periphery of the nucleus.
Drumstick and Barr body are two structures of the nucleus of cells. Both structures contain inactivated X chromosomes.
Key Areas Covered
1. What is Drumstick
– Definition, Facts, Importance
2. What is Barr Body
– Definition, Facts, Importance
3. Similarities Between Drumstick and Barr Body
– Outline of Common Features
4. Difference Between Drumstick and Barr Body
– Comparison of Key Differences
Key Terms
Barr Body, Drumstick
What is Drumstick
A drumstick is a structure in the white blood cell nucleus. Neutrophils, eosinophils, and basophils are polymorphonuclear cells that contain multilobulated shapes in comparison to the other white blood cell nuclei. These nuclei exhibit a characteristic lobed appearance. The separated lobes are connected by chromatin. In neutrophils, the nucleolus disappears during maturation. It can occur in a few other types of cells as well. The drumstick-shaped appendage occurs in 17% of neutrophils in the body. It contains an inactivated X chromosome.
Figure 1: Drumstick in Neutrophil’s Nucleus
Furthermore, X chromosome inactivation or lyonization is inactivating one copy of the X chromosome in female cells. The number of X chromosomes present per female cell is two, out of which one X chromosome randomly undergoes inactivation. It forms heterochromatin, which is transcriptionally inactive. The inactivation of the X chromosome prevents the overexpression of genes on the X chromosome. Although choosing an X chromosome to inactivate is random, the inactivated X chromosome remains inactive for the lifetime. Also, the X chromosome inactivation has a random distribution; around half of the cells in the body contain the inactivated paternal X chromosome, while the other half contains the inactivated maternal X chromosome. Unlike the random distribution of the X chromosome inactivation in placental mammals, the X chromosome inactivation of marsupials applies exclusively to the paternal X chromosome.
What is Barr Body
The Barr body is a structure present in the nucleus of the somatic cells in females. It results from the X chromosome inactivation that occurs in female cells. In species with XY sex determination, females contain two X chromosomes; one with a maternal origin, the other with a paternal origin. Significantly, the process of X chromosome inactivation is called lyonization. Also, the errors in chromosome separation can lead to an extra X chromosome in the daughter cell’s nucleus. The X chromosome inactivation of mammals occurs during the stage of embryonic development. Choosing the X chromosome for lyonization is a random process in mammals, except in marsupials.
Figure 2: Barr Body
Moreover, one Barr body occurs per somatic cell nucleus in genotypical female humans. But a genotypical male does not contain a Barr body. The Barr body is visible in the interphase as a darkly staining small mass. It is in contact with the nucleus membrane. Also, the Barr body occurs at the rim of the nucleus in neutrophils. Additionally, the number of Barr bodies in the somatic cells determines the number of X chromosomes in the nucleus. For instance, in Klinefelter syndrome (47, XXY), a single Barr body occurs in the nucleus. But in 47, XXX karyotype, two Bar bodies are in the nucleus.
Similarities Between Drumstick and Barr Body
- Drumstick and Barr body are two structures of the nucleus.
- Inactivated X chromosomes become drumsticks and Barr body.
- Both occur in female cells.
- They help to diagnose genetic femaleness.
Difference Between Drumstick and Barr Body
Definition
Drumstick refers to a structure consisting of a small nuclear mass, about 1.5µ in diameter, which is attached to the body of the nucleus using a thin filament. At the same time, Barr body refers to a small, densely staining structure in the cell nuclei of females, consisting of a condensed, inactive X chromosome.
Structure
The drumstick is a drumstick-like projection coming out from the white blood cells’ nucleus, while the Barr body is the condensation at the periphery of the nucleus.
Occurrence
Drumstick occurs in the nucleus of neutrophils while Barr body occurs in somatic cells.
Conclusion
In brief, the drumstick and Barr body are two structures of the nucleus of female cells. They contain inactivated X chromosomes. They are important for the genetic diagnosis of femaleness. The drumstick is a drumstick-like projection in the nucleus of the neutrophils. Meanwhile, Barr body is a condensation at the periphery of the somatic cell nucleus. Therefore, their structure is the main difference between the drumstick and Barr body.
References:
- Barr bodies detection and Drumstick. Labpedia.net. (2023, July 11).
Image Courtesy:
- “Neutrophils” By Dr. Graham Beards – Own work (CC-BY SA 3.0) via Commons Wikimedia
- “Sd4hi-unten-crop” By User:Dietzel65, Steffen Dietzel – Own Work (CC-BY SA 3.0) via Commons Wikimedia
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