Muscle development : a view from adult myogenesis in Drosophila

In Drosophila the first wave of myogenesis occurs in the embryo to produce the larval muscles. This musculature undergoes histolysis and largely disappears during metamorphosis, while a second wave of myogenesis begins to generate the muscles of the adult fly. The core myogenic program is highly conserved among both invertebrate and vertebrate species, and Drosophila embryogenic myogenesis is a well-recognized model for identifying genes and pathways governing muscle development. The more diverse and complex adult musculature is also an attractive model to study some aspects of the myogenic process. The more intense research effort focusing on adult myogenesis since early this century has added greatly to our knowledge. We review here what we know about the development of adult muscles, from the specification and diversification of the adult muscle precursors to their final differentiation. The formation of a functional contractile unit requires integrating multiple tissue interactions. We therefore also describe how muscle cells interrelate with the tendons and the nervous and tracheal systems in the course of development.