Human karyotypes for teaching: (47, XYY)

These karyotypes are from abnormal males. There is a full set of 23 homologous pairs of autosomes, one X and two Y's.


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ZooWeb Number

Original image

Modified image






Each karyotype is available in one of three forms:

  • The original unmodified smear. These may have extra material, and often have some chromosomes crossed, which makes them less useful for a class exercise in which students cut apart and arrange the individual chromosomes..
  • A copy of the original, with extraneous materials removed, crossed chromosomes separated, and all chromosomes separated slightly to faciliate cutting apart of the chromosomes in a printed copy. This form is intended for student use in an introductory biology class.
  • A "key", with the chromosomes arranged in standard order.

These karyotypes are from the Wisconsin State Laboratory of Hygiene. They are intended for use in teaching to help students study human chromosomes. Copyright for these images remains with the State Laboratory of Hygiene, apply to them for permission for any other use than non-profit teaching.

For technical information on the methodology by which these smears were created click here.


Do you have suggestions for this page? Please contact one of the participants or email Larry Phelps (

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