The human Y chromosome: its routine identification and variability.

Different criteria for identifying the human Y chromosome using only conventional staining techniques were evaluated and a procedure based on three of them was developed. It leads to correct identification in 93% of cells even without resorting to differences in size between the Y and the other G chromosomes. The variability in size of the human Y chromosome was assessed in a random group of White men. It was found to be significantly greater than that of all other chromosomes in the karyotype when the comparisons were made in such a way as to avoid the size-dependent component of variation.