Abstract
Embryonic development of the optic nerve of the zebrafish, Brachydanio rerio, was studied by 3-dimensional computer reconstruction from serial section electron micrographs. Growing fibers from retinal ganglion cells had growth cones in contact with more mature fibers from adjacent cell bodies. In the growth pattern optic fibers immediately behind the eye were ordered in such a way that the rectangular coordinates of the fiber positions were approximately proportional to the polar coordinates of their cell body positions. Apparently this transformation is achieved by a simple following mechanism that translates the time and position of ganglion cell differentiation into a well-defined spatial organization within the optic nerve.