Development of the Xenopus laevis optic nerve was studied by light and electron microscopy from embryonic stage 26, before the retina has formed, to juveniles, 8 months postmetamorphic. Low-power EM photographs of sections through the retinal optic nerve (RON), middle optic nerve (MON) and chiasmatic optic nerve (CON) were prepared at different stages and the areas containing large axons (0-5 ^...