Examination: The examination for nuclear chromatin body may be done on a smear or histologic sections. A scraping of epithelial cells from the oral buccal mucosa is commonly used.
Features of the sex chromatin (Barr body or nucleolar satellite):
(1) The maximum dimension is 1 micron.
(2) If the body is in contact with the nuclear membrane, then the edge in contact with the nuclear membrane conforms to the membrane and is smooth. The free edge may be round, oval or pointed.
(3) If the body is not in contact with the nuclear membrane, then it tends to be round or oval.
percent of somatic cells with chromatin bodies =
= (number of countable nuclei with chromatin bodies) / (number of countable nuclei) * 100%
Interpretation:
• A female should have a chromatin body in most of her somatic cells.
• A male should have no chromatin bodies, although a rare cell may contain one.
• The number of chromatin bodies within a cell should be the number of X chromosomes minus 1. An XX person should have 1, XXX should have 2, and so on.
• A phenotypic female who lacks chromatin bodies in her cells may have Turner Syndrome.
• A phenotypic female without drumsticks may have testicular dysgenesis.
The number of cells with chromatin bodies may be decreased:
(1) in a newborn infant (during the first 3 days after delivery)
(2) in a postpartum female (during the first 3 days after delivery)
(3) with estrogen or corticosteroid therapy
