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. 2014 Dec 3;6(6):1759091414562107. doi: 10.1177/1759091414562107

Figure 4.

Figure 4.

Expression pattern of key molecules that direct RGC axon navigation at the optic chiasm of mice. RGC axons expressing Robo receptors reach the optic chiasm region starting at E10-E11. There diffusible Slit molecules shape a repulsion-free corridor that delineates the path the RGC axons grow through. SSEA-1-positive neurons expressing CSPG are also located at the ventral diencephalon helping to establish the general optic chiasm path. Axonal divergence between ipsilateral axons (green), arising at the ventrotemporal retina, and contralateral axons (red), coming from the rest of the retina, occurs at the midline. Ipsilateral axons express EphB1, which is induced by the transcription factor Zic2. At the midline, ipsilateral axons are repelled by ephrin-B2 that is expressed by glial cells. As a consequence of the EphB1/ephrin-B2 interaction, ipsilateral axons turn about 90° to project in the same hemisphere. Contralateral axons do not express EphB1 and ignore Ephrin-B2. In contrast, because they express Neuropilin1, contralateral axons are attracted by VEGF-A also expressed at the midline. Positive interactions between NrCAM and PlexinA1 on contralateral axons and PlexinA1 and NrCAM together with Sema6D at the midline also help promote midline crossing. D = dorsal; N = nasal; V = ventral; T = temporal.