Innervation is essential for the development and differentiation of a sex-specific adult muscle in Drosophila melanogaster.

The adult abdominal muscles in Drosophila are generated de novo during metamorphosis and form a simple and characteristic pattern. Throughout adult abdominal development there is a close association between nerves and myoblasts. However, the role of innervation in adult myogenesis is unclear. In males there is an additional muscle, which is unique to abdominal segment 5 (A5). This male specific muscle forms from the same pool of myoblasts as other dorsal muscles in A5 but develops several distinctive characteristics. Previous work indicates the genotype of the innervation of this male specific muscle may play a crucial role in its proper development, although the part played by innervation in the development of other muscles is unknown. Here we test directly the function of innervation in adult myogenesis in general and for the development and differentiation of the male specific muscle in particular. After denervation at the onset of metamorphosis, muscle growth is impaired although the overall muscle pattern continues to develop. Uniquely, the male specific muscle fails to form. Our results indicate that there is an essential role for innervation during the period of metamorphosis for the formation of a full complement of abdominal muscles and for muscle growth. Furthermore, innervation is absolutely required for the formation of the male specific muscle and the development of its special characteristics.