Fig. 2. Pathway of the self-organization phenomenon. Phase contrast images at the left show pigment distribution in two fragments of different size and shape. A schematic model of MT/pigment re-organization is on the right. (A) Initially, the pigment granules are distributed homogeneously across the fragments and MTs are positioned and oriented randomly. (B) Within a few minutes (for fragments with a characteristic dimension of 20-50 µm), multiple local pigment aggregates emerge, presumably near the minus ends of pre-existing MTs. (C) In the next few minutes, local aggregates nucleate new MTs, some of which pass through other aggregates. (D) Dynein-mediated granule transport along these latter MTs eventually lead to a merging of local aggregates into a single focus and ultimately, to nucleation of a single polar MT aster. Bars, 10 µm