Expression of ParaHox genes in trochophore larva of a mollusc
. Gene expression is visualised as blue stain. (A) Gsx gene expression in stomodeum or mouth (yellow arrowhead) plus the apical sensory organ (black arrowhead) and two groups of cells marking the developing cerebral ganglion (red arrowheads). (B) Xlox gene expression in a semicircle anterior to the anal region (black arrowheads) and in two groups of anterior cells (red arrowheads). (C) Cdx gene expression in a ring around the anal marker (black arrowheads); posterior view. am anal marker, ao apical organ, f foot rudiment, pt prototroch, s stomodeum, sf shell field. Reproduced from ; original publisher BioMed Central.