G-Banding of Chromosomes from Chorionic Villi

  • N. M. Gregson
  • M. Seabright


The direct method of obtaining chromosome preparations from chorionic villi (Simoni et al. 1983) yields good quality metaphases. However, many laboratories find it difficult to obtain satisfactory G-banding. The problem can be overcome by monitoring the effect of trypsin with phase-contrast microscopy, as follows:
  1. 1.

    Examine the slide using an x 40 phase-contrast objective and record the position of a suitable metaphase (Fig. 1 a).

  2. 2.

    Transfer the slide to a staining rack and flood with 10% hydrogen peroxide for 3–5 min. (If the preparation is several days old, 30 s peroxide pretreatment is sufficient.)

  3. 3.

    Rinse off the peroxide with isotonic saline and flood with dilute trypsin.

  4. 4.

    Relocate the metaphase and examine the morphology of the chromosomes during the trypsin treatment.

  5. 5.

    As soon as the chromatids become well defined with a rounded three-dimensional appearance (Fig. 1 b), the slide is returned to the staining rack and flooded with stain (Leishman’s or Giemsa, appropriately diluted with 6.8 Sorensen’s buffer).

  6. 6.

    Rinse off the stain with buffer, blot dry, mount and examine (Fig. 1 c).



Isotonic Saline Chorionic Villus Trypsin Treatment Numerical Aberration Chorionic Villus Sample 
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  1. Simoni G, Brambati B, Danesino C, Rossella F, Terzoli GL, Ferrari M, Fraccaro M (1983) Efficient direct chromosome analysis and enzyme determination from chorionic villi samples in the first trimester of pregnancy. Hum Genet 63: 349–357PubMedCrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1985

Authors and Affiliations

  • N. M. Gregson
    • 1
  • M. Seabright
    • 1
  1. 1.Wessex Regional Cytogenetics UnitGeneral HospitalSalisbury, WiltshireUK

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