Pigmentation of the stria vascularis. The contribution of neural crest melanocytes.

Because all stages of melanogenesis (premelanosome, melanosome and melanin granules) were found in intermediate cells of the rat stria vascularis, they can be classified as melanocytes. The marginal and basal cells of these rat specimens contained no pigment. Early in development, the melanocytes or future intermediate cells are located beneath the strial basal lamina. They penetrate this lamina to insert themselves between marginal cells. Both the melanocytes and marginal cells are believed to participate actively in the tissue rearrangements which ultimately bring the two cell types into intimate structural relationship. The ingrowing melanocytes and the mature, pigmented, intermediate cells which they form are frequently associated with blood vessels. Pretreatment with Dopa to enhance the melanin content of early melanocytes did not enable us to identify their route of migration into the stria.