text: The diverse genome-wide repeats are derived from transposable elements, which are now understood to "jump" about different genomic locations, without transferring their original copies. Subsequent shuttling of the same sequences over numerous generations ensures their multiplicity throughout the genome. The limited recombination of the sequences between two distinct sequence elements known as conservative site-specific recombination (CSSR) results in inversions of the DNA segment, based on the arrangement of the recombination recognition sequences on the donor DNA and recipient DNA. Again, the orientation of two of the recombining sites within the donor DNA molecule relative to the asymmetry of the intervening DNA cleavage sequences, known as the crossover region, is pivotal to the formation of either inverted repeats or direct repeats. Thus, recombination occurring at a pair of inverted sites will invert the DNA sequence between the two sites. Very stable chromosomes have been observed with comparatively fewer numbers of inverted repeats than direct repeats, suggesting a relationship between chromosome stability and the number of repeats.