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. Author manuscript; available in PMC: 2014 Jan 1.
Published in final edited form as: Wiley Interdiscip Rev Dev Biol. 2012 May 25;2(1):97–112. doi: 10.1002/wdev.74

Figure 1.

Figure 1

A. Homogeneously distributed cells through random interactions form unstable aggregates. This forms random variations which are amplified above a threshold at which the patterns become set. Distinct patterns are formed by competition between intrinsic factors (properties of the membranes and extracellular matrix), concentrations of activators and inhibitors and the size of the primordia field. From Jiang et al., 2004. B. Feathers from 2 similarly aged chicken embryos demonstrate stochasticity in the placement of feather buds. The feathers show a similar yet non-identical pattern. Numbers of feathers in each region are indicated. Yellow dots highlight feathers along the midline. Green dots highlight subsequent feather buds. Red dots show the relative position of sequential feather buds.