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Buccal SmearAka: Sex Chromatin Test, Barr Body

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  1. Definitions
    1. Buccal Smear (or Sex Chromatin Test)
      1. Microscopy of cheek cell scraping
      2. Presence of barr bodies suggests 2 X-chromosomes
    2. Barr Body
      1. Inactivated X-Chromosome in each cell of a female
      2. Seen as an intracellular dark spot on microscopy
  2. History
    1. Barr body first identified by Dr. Murray Barr in 1949
    2. Mary Lyon suggested etiology and named it Barr Body
  3. Physiology
    1. All cells in female, turn off 1 of 2 X-Chromosomes
    2. Occurs on day 16 of Embryonic development
    3. Each cell child inherits same inactivated X-Chromosome
  4. Indications
    1. Replaced by karyotype for full chromosomal mapping
    2. Previously used to evaluate abnormal Sexual Development
      1. Delayed Menarche
      2. Delayed Puberty
  5. Procedure
    1. Gently scrape inside of cheek
      1. May use wooden Tongue blade or toothpick
    2. Spread sample onto slide into drop of saline
    3. Dry slide and stain with methylene blue 0.3%
  6. Interpretation
    1. Barr Body: Crumpled dark chromosome seen in cell
      1. Suggests normal female karyotype 46XX

Sex Chromatin (C0036867)

Definition (MSH)In the interphase nucleus, a condensed mass of chromatin representing an inactivated X chromosome. Each X CHROMOSOME, in excess of one, forms sex chromatin (Barr body) in the mammalian nucleus. (from King & Stansfield, A Dictionary of Genetics, 4th ed)
Definition (GO)A structure found in a female mammalian cell containing an unpaired X chromosome that has become densely heterochromatic, silenced and localized at the nuclear periphery. [GOC:hjd]
Definition (GO)A condensed mass of chromatin that represents an inactivated X chromosome. [ISBN:0198506732 "Oxford Dictionary of Biochemistry and Molecular Biology"]
ConceptsCell Component (T026)
MSHD012728
EnglishBarr Bodies, Barr body, Sex Chromatin, Sex Chromatins
Spanishcromatina sexual, cuerpo de cromatina de Barr
Parent ConceptsSex Chromatin (C0036867), X Chromosome (C0043292), nuclear heterochromatin (C1325554), Heterochromatin (C0019397), Sex Chromosomes (C0036869), Cell part (C1178969), Chromatin (C0008546)
SourcesGO, LCH, LNC, MSH, NCI, SCTSPA, SNOMEDCT
Derived from the NIH UMLS (Unified Medical Language System)


buccal smear biopsy procedure (C0581714)

ConceptsDiagnostic Procedure (T060)
EnglishBuccal smear, buccal smear biopsy procedure, Buccal smear for Barr bodies, Buccal smear procedure
Spanishextendido bucal para deteccion de corpusculos de Barr, frotis bucal, procedimiento de extendido de material del carrillo, procedimiento de extendido yugal, procedimiento de frotis yugal
Parent ConceptsBiopsy of soft tissue (C0185275), Non-surgical face biopsy (C0565079), Non-surgical oral biopsy NOS (C0565089), Mouth smear procedure (C0581713), Ambiguous concept (C1274012), Biopsy of upper aerodigestive tract (C1293314), Biopsy of mucous membrane (C0191367)
SourcesLNC, MTH, SCTSPA, SNOMEDCT
Derived from the NIH UMLS (Unified Medical Language System)



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