Polarity and Patterns in the Postembryonic Development of Insects

Publisher Summary The basic embryological phenomena do recur at insect metamorphosis. This chapter describes how work with insects has produced some central information. Developing cells are usually polarized in relation to the main axes of symmetry of the organism. During epigenesis, to the continued accompaniment of growth, the possible destinies of individual clones of cells become progressively defined. Once the developmental identity of a cell is established, it is said to be determined and the process which orders requisite determinations in space is called pattern formation. Often the mechanisms of pattern formation are plastic so that they adapt to interference or loss of parts so as to reconstruct the whole pattern from the available material. This process is termed regulation. After a cell reaches its final determined status, it constructs specialized organelles and synthesizes specific biochemical products it differentiates. Although these five features of developing systems—namely, polarity, determination, pattern formation, regulation, and differentiation are each components of one process, they can, to a certain extent, be treated independently. In this chapter they are discussed in relation to development of postembryonic insects.