Calcium Dependent Intercellular Interaction of the Neural Crest Derivate-melanocytes and the Epithelial Cells of the Vestibular Organ

Abstract

As recently established in several species, the presence of neural crest derivate-melanocytes is essential for the development of the epithelial cells regulating the ion and the potential gradients in the inner ear. The interaction between the melanocytes and the epithelial cells appears to be activated when intracellular Ca²⁺ increases. This may be due to a disturbance of the Ca²⁺ homeostasis under hydropic conditions or to the effect of the Ca-ionophore (A 23187) or hormone ((r-MSH). Lowering of extracellular Ca²⁺ blocked the effect of the drug at the basal level. The interaction of the melanocytes with the epithelial or endothelial cells differs significantly. It is indicated that melanocytes may be under hormonal control and that their activation and intercellular interaction are related to the increase of intracellular Ca²⁺ and may be controlled by extracellular Ca²⁺. Furthermore, we propose that melanocytes provide a regulatory network for the maintenance of the inner ear homeostasis.

Key Words:

• endolymphatic hydrops
• α-MSH
• Ca-ionophore
• motility