Fig. 8. Neural patterns of hb expression. Immunostaining for Hb (black) alone (in F, I, and K) or in combination with engrailed (brown in A-E, G, and H), or even-skipped (red in J, L, and M), or fasciclin II (brown in N). Grasshopper Hb protein is detected in all cells of the neuroepithelium before neuroblast delamination (A), but is then restricted to the newly delaminated neuroblasts (B). At 27%, NBs 6-1 and 6-2 (arrowhead in C) express both engrailed (brown) and Hb (black). At 29%, these same neuroblasts express only engrailed, but the initial GMCs that they have produced do express hb (arrow in D). Mesodermal expression in every segment is found as the mesoderm compacts and takes on a wedge shape (E). As the mesoderm moves out laterally, hb is expressed in the more distal cells in the abdomen (arrowhead in F), and in the more proximal cells at the limb bases of appendage-bearing segments (arrowhead in G). Expression is also seen in peripheral neurons of the leg (arrows in G,H). At 35% of development (I, closer view in K), expression can be seen in mesoderm at the base of the limbs (diamond), and in peripheral neurons of the gnathal segments (arrows in K indicate a few of these in the maxillary appendage) and several within each thoracic leg (arrowhead in K indicates the most distal Hb positive neuron in the T1 leg). By 42% (J, closer view in L, Hb in black, even-skipped in red), the pattern of Hb expression in the CNS resembles the pattern seen in Drosophila (see Fig. 1E,F). (M) A closer view of the lateral T1-T2 region from (J). Grasshopper Hb is expressed by several muscle fibers in the body wall (fibers 3 and 4, arrowhead) and at the base of the legs (arrow). The red staining in M shows eve expression in some pericardial tissue as well as muscle fibers 1 and 2. (N) At 50%, hb expression is still retained in some neurons, including aCC (arrow) and pCC (arrowhead).