Gene expression in Bugula neritina larvae. Column 1: Posterior view. Column 2: Lateral view, with anterior (cc = ciliated cleft) to the left. Column 3: Abapical view except I, apical view. Anterior pointing left. Row 1: BnHox4 expression in the apical disc, the glandular complex (pyriform organ = po), and parts of the internal sac. Row 2: BnSoxB2 expression similar to BnHox4 expression. Row 3: BnSoxE expression in the mesodermal blastema. Row 4: BnBAMBI expression in a trapezoid area including epidermal, mesodermal, and internal cells. Expression is also found in a horseshoe shaped area in the internal sac corresponding to some wall cells. ad, apical disc; ant, anterior; is, internal sac; pos, posterior. Scale bar 100 μm.