Giant melanosomes in the eye of the Dutch rabbit.

Giant melanosomes measuring up to about 5.1 micrometers in diameter were seen in the eyes of rabbits with metallic implants. Somewhat smaller giant melanosomes up to about 2.7 micrometers in diameter were seen in the normal eye of a rabbit. Such melanosomes were not found in eyes of rabbits less than a day old. Some giant Stage IV melanosomes appear to derive from giant Stage III melanosomes with an internal structure similar to that in the normal smaller melanosomes, while others appear to be derived by fusion of smaller melanosomes. There may be yet another mechanism of production of giant melanosomes involving 'vesicular' structures but about this one cannot be certain.