Figure 5.

CISs in the VNE and enlarged NSCs in Pseudopallene sp. (ES 4 and ES 7). Transverse histological sections through ES 4 (A,B) and ES 7 (C,D). The VMR is indicated by dashed vertical lines. Black spots mark small prospective epidermal cells. (A) Anterior portion of walking leg neuromere 1. The apically converging cell processes of three CISs are marked in the VNE (arrows). An apical tangential mitosis in anaphase is visible (arrowhead). (B) Posterior portion of right hemi-neuromere of walking leg segment 1. Apically converging cell extensions of two CISs are marked in the VNE (arrows). Note that the basally displaced nuclei (white spots) of the flask-shaped cells are not fully visible in this section, due to the immigrating cells’ oblique orientation. (C) Anterior portion of walking leg ganglion anlage 1. Note the spindle shape and less intensely stained nuclei of the NSCs (asterisks). One NSC is found in division (arrowhead). The ganglionic neuropil has started to differentiate basally (arrowheads). (D) Posterior portion of walking leg ganglion anlage 2. Note the larger nuclei and more voluminous cytoplasmic compartment of the spindle-shaped NSCs (asterisks). Two divisions are marked (arrowheads). The large apical one relates clearly to a NSC, whereas the nature of the sub-apical mitosis was not unambiguously resolvable in the section series.