Fig. 3. Regulation of hb within the NB6-4T lineage. Embryos double labelled with the lineage marker Eg (magenta), and Hb (green) or the glial marker Repo (green), as indicated. Midline is towards left (A-F) or marked by a dashed line (G,G',H, H'). Insets show Eg expression separately. (A,B,G,G') Wild type. At stage 11 there are four cells generated by this lineage: two Hb⁺ glial cells (arrowheads), one Hb^- GMC and the Hb^- neuroblast (A). At stage 14 the lateral neuronal cluster consists mostly of six cells (B). At stage 13, one of the two glial cells in A has divided again and the three resulting cells have migrated towards the ventral midline: two (MMM3 and MML3) near the midline and one (ML2) left behind (outlined in G'). (C,D,H,H') svp^e22. At stage 11, all four cells (inset in C) are often Hb⁺, indicating a prolonged expression of Hb (C). Concomitantly, the size of the lateral cluster is reduced (D). In many hemineuromeres there is one additional NB6-4T-derived glial cell at the ventral midline (H,H'). (E,F) pros^C7. At stage 11, all four cells are Hb^- (E), showing that Hb expression could not be maintained. The lateral neuronal cluster is enlarged (F), probably due to the deregulation of dacapo. (I) Scheme of NB6-4T lineage development, with markers used in our analysis. Scale bar: 20 µm.