Expression of Euperipatoides kanangrensis collier. (A) Stage 0 embryo. The blastopore begins to form (arrow). Expression of col is around the blastopore. (B) Stage II embryo, lateral view. Diffuse expression (or possibly background) in the head and the posterior segment addition zone (saz) (term introduced in ; also see ). Well-defined expression profile in the head forms two stripes at the anterior ridge of the embryo (arrow). Two clear dots of expression anteriodorsal to the stripes (arrowheads). (C) Early stage IV embryo; ventral view. Expression along the complete trunk is on the same level as the limbs. Note that this expression is discontinuous at the base of the limbs that do not express col (asterisks). (D) Late stage IV embryo; ventral view; flatmounted. Complex strong expression in the brain (large arrow), with a dominant spot-like domain in each hemisphere (small arrow) and faint dot-like expression at the anterior rim of the brain lobes (open arrowhead). Expression between the bases of the limbs persists, but still no expression in the base of the limbs (asterisks). Faint expression appears in the tips of all appendages and the two anterior-most lip bulges (filled circles). Expression begins in the central nervous system associated with the anterior trunk segments (or ventral organs; discussed in  (closed arrowhead). Note that unspecific expression appears on the surface of the antenna, possibly because of beginning cuticle formation. Abbreviations: bl, brain bulb; fap, frontal appendage; L1, first walking leg; L15, 15th walking leg; sp, slime papilla; saz, segment addition zone.
Janssen et al. BMC Evolutionary Biology 2011 11:50 doi:10.1186/1471-2148-11-50