Cell behaviour during postembryonic pattern regulation in the insect abdomen (Oncopeltus fasciatus). I. Regeneration of segment borders.

The confrontation of cells from the anterior region of an abdominal segment of Oncopeltus with those from the posterior region of the same or the adjacent segment results in the generation of a segment border. The behaviour of epidermal cells during this regulation is described. It consists primarily of cell division and transverse elongation of cells at the site of confrontation. This behaviour can be separated from any associated purely with wound healing because a similar-sized wound to that used to ablate the segment border, performed within the segment, does not result in any cell division or elongation. The results are consistent with the view that there is a discontinuity in positional values at the segment border. The stability of such a discontinuity and the regeneration of segment borders are discussed in terms of there being a special population of cells at the segment border that have the property of isolating other cells with the maximum difference in positional values.