Fig. 6. (A-E) Expression patterns of the neural anti-HRP and anti-acetylated tubulin antibodies (green) and morphology of the neuromeres; double-staining with phalloidin-rhodamine (red). Confocal micrographs of flat preparations of prosomal neuromeres (A,B,D,E), an opisthosomal neuromere (C) and light (F,H,I) and electron micrographs (G) of transverse sections through the fourth prosomal neuromere at 240 hours (A-C), 280 hours (D,E), 250 hours (F,G,I) and 300 hours (H); anterior is towards the top (A-E); medial is towards the left (F-I). (A,E) The HRP antigen is expressed on the axons of the invaginated cells and in addition in the apical cells (arrows). (B,C) Acetylated tubulin is expressed in the cells that remain in the outer layer, but not in the axons of the invaginated cells (arrows). (D,F) The epidermis overgrows the neuromeres at the end of neurogenesis (arrows in D; arrowheads in F). (G) Higher magnification of a similar region framed in F. Ultrastructural analysis reveals that the neurones and axons (asterisks) are not covered with epidermal cells. (H) At 300 hours the epidermal cells have completely overgrown the ventral neuromers. (I) At 250 hours the epidermoblasts (asterisks) can be distinguished morphologically from the surrounding cells. Neurones at the border of the ventral neuromer are marked with black dots. 12, walking leg 2 corresponding to the fourth prosomal segment; o2, second opisthosomal segment; 1c, longitudinal connective; c, commissure; vn, ventral neuropil. Scale bars: in A, 100 µm for A,B; in C, 50 µm for C-E; in F, 20 µm for F; in G, 4 µm for G; in H, 20 µm for H; in I, 15 µm for I.