The fine structure of melanogenesis in coat color mutants of the mouse

Melanogenesis in the eyes of various pigment mutants of the mouse was examined by electron microscopy. It is apparent from the results that premelanosomes in the choroid and the retina of most mutants studied have essentially identical developmental characteristics. Although the pigment mutations affect the size, shape, and distribution of the granules, the major effect common to most of them is the premature termination of melanization of the premelanosome filaments. It seems probable that melanogenesis in both the choroid and retina follows a common pathway, and possible sites of action by gene mutations on this pathway are discussed.