Proximo-distal development in the legs of Drosophila.

The appendages of insects and vertebrates develop as extensions of the body wall. During development, a proximo-distal axis for growth and patterning is created in each appendage, in order to specify appendage length and allocation of pattern elements like joints and sensory organs. Here we use the expression of molecular markers to examine how PD development takes place in the legs of the fruit-fly Drosophila melanogaster. The data suggest a process of regionalization and progressive subdivision of an anlage similar to both insect embryonic segmentation and vertebrate somitogenesis.