1. V. J. Hearing andM. A. Lutzner, Yale J. Biol. Med.46, 553 (1973).
2. P. Doezema, J. Cell Physiol.82, 65 (1973).
3. M. A. Lutzner andC. T. Lowrie, inPigmentation: Its Genesis and Biologic Control (Appleton-Century-Crofts, New York 1972, p. 89.
4. V. J. Hearing andM. A. Lutzner, J. Ultrastruct. Res.43, 88 (1973).
5. J. N. Dumont andJ. J. Eppig Jr., manuscript in preparation.