Fig. 4. Mapping ipsilateral and contralateral projecting RGCs in Foxg1^+/+ and Foxg1^Cre/Cre embryos by retrograde tract tracing from the optic tract growing over the thalamus at E15.5. (A-H) Wild type. (A,B,G) DiI and DiA double-label experiment showing predominance of contralateral (con) projections (A,B) at the optic chiasm (oc) and (G) in the retina; an ipsilaterally (ips) labelled cell (red) is marked with arrow in G. (C-F,H) Single DiI-labelling experiments. (C,E) At the optic chiasm, the majority of labelling is in the contralateral optic nerve (on). (D,F) In the contralateral retina (F) a large number of labelled cells are distributed both nasally and temporally. (D) In the ipsilateral retina, far fewer cells are labelled. (I-O) Mutants. (I,M,N) Double-label experiment showing (I) the optic chiasm and (M,N) ipsilaterally (red) and contralaterally (green) projecting RGCs in the retina (note the absence of double labelled, yellow, RGCs). (J-L,O) Single label experiment showing increased ipsilateral labelling (compared with wild type) in (K,K') both nasal (n) and temporal (t) parts of the elongated retina (er) and (J-L) their axons in the mutant correlate of the optic nerve (on^*). (H,O) Higher magnification showing the disposition of RGCs in (H) wild-type and (O) mutant retina. All sections are horizontal with anterior (nasal) at the bottom. Each asterisk indicates which optic tract was injected with DiI (red) and DiA (green). Broken lines indicate the ventral midline. Scale bars: 500 µm in A; 100 µm in B,C,G,I,J,M; 200 µm in D F,K,L; 50 µm in H,N,O.