The chromosome in situ hybridization with human X chromosome alpha satellite DNA 
probe (pBamX7) on human lymphocyte metaphases and interphase nuclei was 
performed for interphase cytogenetic studies. The individuals with numerical or 
structural abnormalities of X chromosome were studied. The results showed that 
the probe hybridized specifically to the centromeric region (p11----q11) of X 
chromosome. The number of silver grain clusters in interphase nuclei was 
correlated with that of X chromosome. Most of the clusters located near the 
nuclear membrane where inactive X chromatins (Barr-bodies) were usually found. 
The method of ascertaining the number of X chromosomes by in situ hybridization 
was much more reliable than that by counting the number of Barr-bodies. The 
modified R-banding technique was introduced and the significance of this work 
was also discussed.