My objective is to determine: (1) the nature of the anomalous retinal projections associated with oculocutaneous hypopigmentation; (2) if retinal hypopigmentation rather than cutaneous or other ocular hypopigmentation is correlated with anomalous retinal projections. Subjects will be mice of a single inbred strain (C57BL/6J) which are littermates that differ in pigmentation but are otherwise genetically identical (coisogenic). In each mouse one optic nerve will be cut and allowed to degenerate. Then each brain will be sectioned and stained, and the distribution of degenerating axon terminals in the lateral geniculate nucleus will be mapped from photomicrographs. (1) To determine the nature of the "albino anomaly" I will compare oculocutaneously pigmented (black) vs unpigmented (albino) mice. Post-operative time allowed for degeneration of the severed optic nerve axons will vary; this will permit assessment of the projections of different types of axons with differing rates of degeneration. If the albinos' uncrossed retinogeniculate projection is smaller than the blacks' at all survival times, then one may conclude that the "albino anomaly" is a general reduction in the number of uncrossed retinogeniculate axons. However, an uncrossed retinogeniculate projection in the albinos which is not always smaller than the blacks' will show that the anomaly is not a general change but rather a specific change in the fiber composition of the uncrossed projection. (2) To test the "retinal hypopigmentation hypothesis" I will compare retinally pigmented vs retinally unpigmented mice that do not differ in coat color. A dark-eyed vs pink-eyed difference will show that retinal pigmentation is a factor in visual system development when non-retinal pigmentation is held constant. Also, I will compare cutaneously pigmented vs cutaneously unpigmented mice that do not differ in retinal pigmentation. A black-coat vs white-coat difference will show that non-retinal pigmentation is a factor in visual system development when retinal pigmentation is held constant. These studies are relevant to work on human syndromes (e.g., strabismus), neurological mutants, recovery of function, and comparative neuroanatomy.