Muscle development during vertebrate limb outgrowth

Limb development has become one of the model systems for studying vertebrat e development. One crucial aspect in limb development is the origin, differ entiation and patterning of muscle. Much progress has been made in recent y ears towards understanding this process. One of the general observations is that the genes involved in limb muscle development appear to be very simil ar to those involved in muscle development in other regions of the embryo. In this review, we summarize some of the genes and mechanisms that regulate limb muscle development and discuss various avenues along which a deeper u nderstanding can be gained of how muscle cells originate and differentiate in different tissues during vertebrate development.