In C. elegans, induction can be very precise with individual cells producing specific effects in just two or three neighboring cells. Pattern formation triggers the sequence of events that will lead to organ development and morphogenesis. For example, the webbing tissue between the fingers in humans will die before the infant is born. Plant cells do not move, but cytoskeletal elements direct cell division and expansion to form the plant body pattern. Plants also have organ identity genes that interact to cause formation of sepals, petals, stamens, and carpels.
Positional information is used by organisms as a basis for pattern formation.
Positional information, and its influence on chick wing development, is well understood. Gradients of morphogens are established in the embryo and work with the zone of polarizing activity to provide important positional information. Cells at different distances from the zone of polarizing activity are exposed to different concentrations of the morphogens and respond differently. Studies of Drosophila melanogaster have provided a great deal of information about the development of body segmentation . A gene cascade controls segmentation and pattern formation in Drosophila.