It was first identified in Barr and Bertram's experiments with cats, and this structure can now be determined by its positive stain in the Feulgen [fell-gen] reaction.   This highly condensed structure lies against the nuclear envelope of interphase cells, and its existence was finally explained by the hypothesis formulated by Liane Russell and Mary Lyon.  The number of them that are present follows an N-1 rule, where N is the total number of X chromosomes present.  Also
It was first identified in Barr and Bertram's experiments with cats, and this structure can now be determined by its positive stain in the Feulgen [fell-gen] reaction.   This highly condensed structure lies against the nuclear envelope of interphase cells, and its existence was finally explained by the hypothesis formulated by Liane Russell and Mary Lyon.  The number of them that are present follows an N-1 rule, where N is the total number of X chromosomes present.  Also known as a sex chromatin body, FTP, name this structure that is an inactivated X chromosome.
It was first identified in Barr and Bertram's experiments with cats, and this structure can now be determined by its positive stain in the Feulgen [fell-gen] reaction.   
Barr body