The X chromosomes of man and mouse

Many chromosomal segments with the same
sequences of two or more homologous loci are
syntenic (on the same chromosome) in mouse
and man. Gene loci sequences on the X chromosomes
of eutherian mammals are especially
similar owing to the conserving effect of X inactivation.
In the X chromosomes of humans and
mice, there are five blocks of gene loci that have
the same sequences, although they are in different
regions and in part oriented in different
directions;