The morphological diversity of the vertebrate limb is the result of finely tuned responses to signals that emanate from organizer centers controlling the three embryonic axes that shape the limb throughout processes such as apoptosis, differential growth and cell differentiation. When the autopod begins to form, an undifferentiated group of cells subjacent to the Apical Ectodermic Ridge (AER) respond to chondrogenic or pro-apoptotic signals. In this review, we briefly describe some experiments that identified the principal signals responsible for promoting cartilage differentiation and cell death. As the interdigit has a chondrogenic potential, we discuss the existing balance between chondrogenic and apoptotic signals that setup the digit-interdigit pattern for establishing the undifferentiated autopodial cells destiny.
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