文摘
The phylogenetic location of hemichordates is unique because they seem to fill an evolutionary gap between echinoderms and chordates. We report here characterization of Pf-otx, a hemichordate ortholog of otx, with its embryonic and larval expression pattern. Pf-otx is initially expressed in the vegetal plate of the blastula. Expression remains evident in the archenteron through gastrulation and then disappears. A new expression domain appears near the mouth along the preoral and postoral ciliated bands in the early tornaria larva.