Figure 9.

Expression patterns of Pdu-Hes4 and their schematic representations in Platynereis larvae and during posterior elongation (PE). Whole-mount in situ hybridization (WMISH) for the different stages indicated on each panel is shown. From 33 to 48 h post fertilization (hpf), Pdu-Hes4 is expressed predominantly in two columnar brain cells in the dorsal part of the larvae, in the stomodeum and in the mesoderm of the (presumptive) parapodia. At 72 hpf, an intense expression is found in the developing cone-shaped midgut and mesodermal segment addition zone (SAZ). During PE, this gene is broadly expressed in the segment epidermis of well-developed segments (in the ventral side), in the midline, in the ectodermal SAZ as well as the dorsal blood vessels. For the larvae, panels are ventral views (anterior is up). Expressions patterns during PE are shown for both sides (anterior is up), V = ventral, D = dorsal. Deeper ventral view (different focus plane) is highlighted in red for 33hpf larvae.