In the coming year we propose: (1) To continue our studies of the dvelopment of the avian visual system examining in particular, the occurrence and elimination of naturally occurring and induced developmental errors in this system, its capacity for regeneration after early experimental manipulation, and the establishment of polarity in its two principal components, the retinal ganglion cells and the optic tectum; (2) To assemble a new computer/microscope system for the acquisition and collation of neuroanatomical data, including the three-dimensional reconstruction of neurons from tissue sections; (3) To raise monoclonal antibodies directed against retinal and tectal neurons and against certain defined antigens including some of the known transmitter synthesizing enzymes. This work is to be carried out in the newly-completed Weingart Laboratory for Developmental Neurobiology at the Salk Institute.