 Later work identified more pair-rule genes in the "Drosophila" early embryo – "fushi tarazu", "odd-paired" and "sloppy paired".Once the pair-rule genes had been identified at the molecular level it was found that each gene is expressed in alternate "parasegments" – regions in the embryo that are closely related to segments, but are slightly out of register.Each parasegment includes the posterior part of one (future) segment, and an anterior part of the next (more posterior) segment.