Reporter construct studies indicate that Lim3 is co-expressed with tup in a subset of motor neurons. For the intersegmental nerve, all the ISNb-specific motor neurons express both Lim3 and tup, while those projecting in ISNd only express tup. Lim3 is not co-expressed with tup or ap in interneurons. Motor neurons co-expressing tup and Lim3 include motor neurons RP1, RP3, RP4, RP5, the contralateral V motor neuron which innervates muscle 12, and MN28 and MN14/30 which innervate muscles 28 and 14 plus 30, respectively. The tup-expressing motor neurons projecting in ISNd innervate muscles 15-17.
Reporter expression is not detected in neuroblasts but in postmitotic neurons, in a subset of motor neurons and interneurons. The subset of motor neurons expressing the reporter innervate muscles located ventrally in the body wall, and include RP1, RP3 and RP4. Reporter expression is detected in 3 morphologically different classes of interneurons. Double staining for ap and tup reporters reveal that they are expressed in nonoverlapping subsets of neurons that project axons along different pathways.