Fig. 3
From: Unexpected co-linearity of Hox gene expression in an aculiferan mollusk
Morphology of Acanthochitona crinita trochophore larvae. Anterior faces up. a, b Mid-trochophore larvae. Episphere and hyposphere are separated from each other by the prototroch. In the dorsal hyposphere region, the anlagen of the seven shells are surrounded by spicule-containing cells. c, d Late trochophore larvae. Seven differentiating dorsal shell plates are present. at apical tuft, ds dorsal shell plates, f foot, pt prototroch, sc spicule-forming cell(s)