Figure 9. Position of dorsal and ventral axons in optic nerve near the chiasm at PND1.

The same analysis of the distribution of label done for the optic tract (Figure 8) was performed on the optic nerve within 200 μm of the optic chiasm, with no consistent preference for label of dorsal (shown in green) or ventral (shown in red) axons in any sector of the nerve. Panels A, B and C show the pattern of axons in the optic tract of a PND1 mouse whose eye was injected dorsally (A, green) and ventrally (B; red) on the day of birth. C is the overlay. Panels D, E and F illustrate a similar series of data for a second animal and reveal a very different distribution of label, with no consistent pattern between animals. Whether the optic nerve is divided into dorsoventral (G) or mediolateral (H) halves, no statistically significant difference in the distribution of the labels can be distinguished. 50 μm scale bar and orientation of section (dorsal-up, ventral-down, medial-left, lateral-right) shown in A applies to all panels.