Fig. 4
Expression of Pdu-sp/btd during caudal regeneration of Platynereis dumerilii (16 dpa). In situ hybridizations, anterior is to the left for (a–e). a Ventral view of the regenerated posterior end. The red line marks the site of amputation. Regenerated tissues are to the right. The last mature segment is on the left side. b Ventral view of Pdu-sp/btd expression in single cells at the base of the anal cirri (black arrows). c, d Shifting expression domains of Pdu-sp/btd in developing notopodia (black arrowheads). e Pdu-sp/btd exhibits expression at the base of developing neuropodia (white arrowheads). An additional expression domain is located in the central nervous system near the segment boundary light gray arrow heads). The gut tissue exhibits moderate Pdu-sp/btd expression. f–h Optical transverse sections of segments in different stages of maturation with focus on parapodia, ventral side down. Expression domains indicated in c–e are labeled accordingly (ac) anal cirri, (dc) dorsal cirrus, (g) gut, (nep) neuropodium, (nop) notopodium, (pb) parapodial bud, (pp) parapodia, (vc) ventral cirrus. Scale bar equals 200 µm