Modulation of melanocytes during experimentally induced endolymphatic hydrops.

The presence of melanocytes is required for inner ear function. The relationship between melanocytes and inner ear function is not yet known in detail. Melanin scavenges Ca++. The alterated Ca++-homeostasis by experimentally induced endolymphatic hydrops (animal model for Ménière's disease) stimulates the melanocytes to motion which results in dispersion of melanosomes and/or dislocation towards areas of transmembrane ion/fluid transport, e.g. secretory cells or capillaries. The intracellular increase of Ca++ initiates formation of membrane invaginations and vesicles seen frequently on the side facing capillary and occasionally in the neighborhood of basal infoldings of the epithelial cells. These findings suggest an active exchange of ions and/or compounds between the melanocytes and endothelial and/or epithelial cells enhanced by pathological conditions. Finally, an increase of Ca (or Ca-associated mechanism) enhances the melanogenesis in the melanocytes.