Development of Larval Body Wall Muscles

Abstract

Publisher Summary Larval muscles in Drosophila form a complex pattern of contractile fibers that attach to the inner surface of the developing epidermis. Each segment has its own, highly specific set of muscles, but from the point of view of the neuromuscular junction, most attention has been focused on the muscles of the abdominal segments. The formation of the muscle pattern depends on an interaction between a general pathway of myogenic differentiation and local controls that endow individual muscles with their special characteristics. Each muscle synthesizes a contractile apparatus and anchorages to the epidermis and forms a neuromuscular junction with the terminals of innervating motor neurons. These functions are common to all muscles and, at least in part, are downstream of control factors such as Dmef-2 . However, each muscle in the pattern has its own highly distinctive properties, including size, shape, orientation, sites of attachment, and innervation by particular motor neurons. These individual properties depend on the local expression of transcription factors such as S59 and Kr . The combination of general and specific regulatory mechanisms in the myogenic pathway leads to the formation of a specialized set of contractile elements on which motor neurons can act to produce the coordinated movements of larval behavior.