Barr body Information and Courses from MediaLab, Inc.

These are the MediaLab courses that cover Barr body and links to relevant pages within the course.

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Variations in White Cell Morphology - Granulocytes
Barr Body A Barr body appears as a small drumstick-like projection on one of the lobes of a some of the neutrophil in females. Barr bodies are attached to the nuclear lobe by a single narrow stalk which distinguishes them from other thicker projections, sometimes referred to as "clubs." Clubs have a thicker, and sometimes, a double stalk. This projection can be seen in both males and females and has no clinical significance. Barr bodies must also be distinguished from hair-like projections sometimes seen in the band form, following irradiation or in patients with a malignant tumor that has metastasized. Since Barr bodies are the morphological expression of the inactivated X chromosome, one Barr body can be seen in up to 3% of the neutrophils on a female's peripheral blood slide. In rare chromosome disorders in which three or more X chromosomes are present, two to three Barr bodies per neutrophil can be seen. Recognition of a Barr body in a neutrophil is important in order to avoid reporting it as abnormal unless two or more per neutrophil are seen.	View Page
Barr Bodies may be Normal or Pathological The Barr body is considered nonpathological unless associated with the rare chromosome disorders, in which case it would be pathological.	View Page
Barr Body This neutrophil has four lobes. A Barr body is present on the lobe in the lower right corner of the cell.	View Page
Which of the following best describes a Barr body?	View Page
Another Barr Body There is a Barr body on the lobe at 6 o'clock on this neutrophil. It is not quite as distinct as in the previous example.	View Page

White Cell and Platelet Disorders: Peripheral Blood Clues to Nonneoplastic Conditions
The nuclear appendage at the tip of the arrow is a normal finding in females but not in males.	View Page
The small club-shaped(drumstick)nuclear appendage attached to one lobe of a neutrophil (marked by the blue arrow in the photograph) may be found in:	View Page