Small vesicles containing pigment inside of pigmented fish epidermal cells aggregate or disperse in response to treatment with certain chemicals. When nocodazole is added to cells in which the pigment granules have been induced to aggregate, the granules cannot disperse again. Pigment granules can either aggregate or disperse. Once aggregated the granules cannot disperse again, and vice versa. Pigment granule dispersal is a microtubule-dependent process. Intermediate filaments have a large effect on the pigment granule dispersal process and can stabilize resulting aggregates.