Fig. 1

Ipsilateral retinal axons penetrate ventral dLGN from their early ingrowth. Coronal sections through the dLGN following the transport of fluorescent CTB from the eye. Ages and genotypes as marked. Left hand column shows contralateral (Contra) projections, while the middle column reveals ipsilateral (Ipsi) terminals. A merged image is shown on the right (green: contra; red: ipsi; blue DAPI counterstain). A, B In P0–1 WTs (A) contralateral axons had invaded and filled the body of the dLGN. Ipsilateral axons had a much more restricted distribution within the nucleus (A′). Axons tended to stay confined to the optic tract overlying the ventral part of the dLGN. Upon entering (arrow), they then fanned out slightly but targeted the dorsomedial segment of the nucleus. The relationships between the two groups of axons can be seen more clearly in the merged image (A″). In KO mice (B), contralateral axons similarly filled the dLGN. Ipsilateral axons (B′), however, showed a very different pattern to WTs. Most notably, the axons entered the dLGN near its ventrolateral border (arrow). The projections extended along the DM-VL extent of the nucleus, as seen in the merged image (B″). C, D By P3–4, WT (C) contralateral label was reduced in the dorsomedial segment compared to other regions of the nucleus (*) and the ipsilateral label had begun to consolidate in this area (C′, C″). In Ten-m3 KO mice (D), there was a reduction in the density of contralateral label in a band which ran the length of the nucleus, including the ventral area (*). Ipsilateral label was beginning to consolidate in this region (D′, D″). Dorsal (D) is to the top and lateral (L) to the right of each image, as marked in A″. Scale bars: 200 μm