Observations on the structure of the eumelanosome matrix in melanosomes of the chick retinal pigment epithelium



Eumelanosomes from the developing chick pigment epithelium have been isolated, solubilized, and the residue collected. Examination of this material in the electron microscope provides evidence for new structural entities in the eumelanosome and information on the organization of the melanosome. This evidence suggests that there are (1) 190-Å fibers arranged in a zigzag fashion, surrounding 240-Å–diameter electron-lucent spaces and (2) an internal gridwork enclosing 40–50-Å-diameter spaces. These two structures are probably alternately layered and “rolled-up.”