Pattern control in insect segments: superimposed features of the pattern may be subject to different control mechanisms.

The integument of an insect segment displays two distinct pattern features which are based on different properties of the constituent epidermal cells. Normally, the uniform orientation of epidermal cell polarities ("polarity pattern") is strictly correlated with the sequence of differentiated cells ("differentiation pattern"). Here it is reported that in the integument of the cotton bug Dysdercus epidermal cells can adopt orientations that do not correlate with the pigmentation pattern and which are not compatible with the gradient model. The results indicate that different features of a composite pattern can be independently controlled.