Figure 1.

Anatomy of the visual system and the neuromuscular junction. (A) Perspective diagram of R cell axons projecting out of the retina, into the lamina and medulla, during pupal development in wild type. R cells (R1–R8) and lamina neurons (L1–L5). (B) Illustrative example of R1–R6 axons failing to extend to targets in the lamina, and R7 axons innervating the inappropriate target layer in the medulla, as would be seen in N-cadherin mutants. (C) Example of R8 axons failing to choose the appropriate layer in the medulla, as seen in a capricious mutant. (D) Example of R1–R6 axons extending to aberrant targets in the lamina, as seen in flamingo mutants. (E) Anatomy of the wild-type neuromuscular junctions in a single larval hemisegment. (F) Example of en passant synapse formation, as seen in flamingo mutants. (G) Example incorrect innervation of the target field, as seen in capricious mutants.