DIVERSITY AND DEVELOPMENTAL REGULATION OF EXTRAOCULAR-MUSCLE - PROGRESS AND PROSPECTS

The developmental regulation of skeletal muscle phenotypes has attract ed much attention from cell and molecular biologists. Myogenesis serve s as an excellent model of the interaction of genetic and epigenetic e vents in determining definitive adult characteristics. The muscles tha t are responsible for eye movements are among the most structurally an d functionally diverse mammalian skeletal muscles. Despite these uniqu e attributes, the extraocular muscle has been studied less extensively than the traditional limb and diaphragm models. This review explores current concepts regarding the development of these muscles. Proper in terocular alignment and coordination of eye movements are essential fo r normal vision in the adult. Moreover, coordinated oculomotor functio n during the perinatal period is critical for the normal development o f the visual system. Therefore, a thorough understanding of the sequen ce of events and mechanisms that regulate extraocular muscle developme nt and maldevelopment is vital. Studies related to myoblast origin and differentiation and to the role of genetic versus environmental facto rs in shaping and maintaining adult extraocular muscle phenotype are r eviewed. Prospects for understanding the cellular and molecular mechan isms that regulate the heterogeneity and plasticity of these muscles a lso are discussed.