Comparison of segment development among annelids

We know there are some genes responsible for the body segmentation through research done with Drosophila melanogaster. Some examples of these genes are engrailed and wingless, that belong to the segment-polarity genes class, and even-skipped, hairy and fushi-tarazu belonging to pair-rule gene class (Davis, G. k. and Patel, N. H., 1999). Engrailed is conserved among arthropods and has been shown to function like a segment formation gene in annelids. The expression of segment-polarity genes has been characterized in few annelid species and the expression patterns vary among the species characterized (Seaver, E. C. and Kaneshige, L. M., 2006). I intended to compare the development of segment formation among three annelid species, Boccardia proboscidea, Notomastus sp. (Capitellidae family) and Spirorbid sp. Beyond the comparison of segment development, I intended to see if they have similar expression patterns, or vary among the species