Normal lens cell behavior is characterized by regulated cell replication and specialized gene expression. However, loss of such regulation is sometimes associated with development, aging, and the premature malfunctioning of the lens cell nucleus through the technique of cell reconstruction and nuclear transfer, the capability of the nucleus to take part in cell replication and gene action can be evaluated. These experiments will be carried out to demonstrate the regulation of function of the lens epithelium in different conditions: the embryo, the adult, the cataractous and other abnormal states. The "in vitro" and in vivo" approach adopted in this proposal will elucidate the factors regulating lens function and the disturbances associated with development, aging and inherited cataractous abnormalities. The use of mammalian cells and embryos has the advantage that the results obtained from the outlined experiments will be relevant to the pathological conditions found in the human lens.