Figure 6
Position of the Pdu-Ngn - and Pdu-ASH -expressing cells with respect to the apicobasal organization of the prospective ventral nerve cord region. Confocal picures of double WMISH are shown. The probes which have been used are indicated on the pictures. A and C are superficial plans, B and D more internal ones. Pdu-Ngn and Pdu-ASH are mainly expressed in superficial cells while Pdu-elav is mainly expressed in more profound cells. F to J are virtual cross-sections, sections have been made at two anteroposterior levels (1 and 2) as indicated on a schematic drawing (E). Apical is up, basal is down. Pdu-Ngn and Pdu-ASH are mainly expressed in the apicalmost layer of cells of the prospective VNC while Pdu-elav, Pdu-syt, and Pdu-TrpH are expressed in more basal cells. Some internal cells also express Pdu-Ngn (H) and Pdu-ASH (not shown) and on some confocal sections we can see rare cells co-expressing Pdu-Ngn or Pdu-ASH and Pdu-elav. Such co-expressions are never observed with Pdu-syt or Pdu-TrpH. The white asterisk indicates an expression in the stomodeum. K summarizes the apicobasal layering of the Platynereis prospective VNC based on the data published by Denes et al. [35] and includes the expression of Pdu-Ngn and Pdu-ASH defined in this study. Apical is up, basal is down. Pdu-elav expression domain is in green, Pdu-ASH and Pdu-Ngn expression domain is in red, and the yellow region indicates the zone of overlap of these expression domains.