Exhibits excessive branching in the dorsal cluster of the dorsal cluster of embryonic dendrites. In about 80% of mutant embryos, both dorsal and lateral dendrites branch excessively to produce numerous overlapping branches, unlike the wild-type in which branching of these dendrites happen only once or twice before the segment boundary is reached. Mutants also exhibit axonal outgrowth and misrouting defects, and the number of neurons, epidermal cells and muscles cells in each hemisegment are reduced in number, but increased in size. Neuron size in the central nervous system is also bigger than wild-type, and the axon tracks are less tightly packed. The size of the embryo appears normal. Unlike wild-type, in mutant embryos, dendritic outgrowths emerge in many different directions from the primary dorsal dendrite and branching occurs prematurely - before the primary dorsal dendrite has elongated. Mutants show no gross defects in anterior-posterior or dorsal-ventral patterning.