Differentially expressed Dpr and DIP genes reveal an MN that solely innervates m23. (A) Schematic of transverse muscles 22, 23 and 24 (gray) with previously identified MN22/23-Ib (green), MN23/24-Ib (red) and newly identified MN23-Ib (blue). (B) Representative image showing dpr13-GAL4 expression in both MN23/24-Ib (red arrowheads) and MN23-Ib (blue arrows). Thus, all boutons on m23 and m24 are labeled by GFP. (C) Representative image showing DIP-β-GAL4 expression in MN23-Ib (blue arrow). Boutons underneath m23 and boutons from m22, m24 (red arrowheads) are not labeled by GFP, thus DIP-β-GAL4 is not expressed in MN22/23-Ib and MN23/24-Ib. (D) Representative image showing dpr5-GAL4 expression in MN22/23-Ib and MN23/24-Ib (red arrowheads), but not in MN23-Ib (blue arrow). The lack of GFP in the arbor on m23 indicated the existence of an MN that solely innervates m23.