Genes encoding interacting receptors show compatible spatiotemporal expression. Genes encoding interacting receptors are paired (gene 1, gene 2) and listed vertically; homophilic interactions were treated separately below. The expression in anatomically distinct regions of the nervous system at different stages of embryonic development is indicated by appropriate shading within the grid. Expression key: gene 1 only = gold; gene 2 only = blue; co-expression = pink; no expression = grey; hatched = both expressed at the same stage outside the nervous system but not in identical or neighboring tissues; cross = expression not determined for one of the two genes. Stages: S = 14 to 19 somites; P = Prim5; Lp = Long-pec; L = Larval (4 to 5 days post-fertilization). CNS = central nervous system.