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. 2012 Jun 7;7(6):e38566. doi: 10.1371/journal.pone.0038566

Figure 7. EphA3 ectodomain overexpression alters the topographic map formation.

Figure 7

After infection of the optic tectum at E2 with RCAS-BP-B-EGFPF (control) (A) or with RCAS-BP-B-EphA3ΔC-EGFPN3 (B) and DiI labeling of the naso-dorsal retina at E16, the retina and the tectum were analyzed in whole mounts at E18 (A, B). Graphs represent retinal whole mounts labeled in naso-dorsal areas (ND) with DiI (black circles) (upper) and tectal whole mounts where the corresponding DiI labeled RGC axons (drawings) are shown in microphotographs. (A) Optic fibers (OFs) pass throughout the intermediate tectum (arrowheads) and form a termination zone (TZ) (arrow) over an area of EGFPF expression in the corresponding target area (caudal tectum) in a control tectum. (B) OFs pass through the target area (caudal tectum) without producing TZs (arrowheads) in a tectum where EphA3ΔC-EGFP was overexpressed. N: nasal, T: temporal, V: ventral, D: dorsal, R: rostral, C: caudal. Scale bars  = 50 µm. (C–F) Graphs show the proportions of temporal (C, E) and nasal (D, F) OFs which form TZs in the rostral and the caudal tectum respectively in EGFPF-expressing tecta versus EphA3ΔC-EGFP-overexpressed tecta. (C, D) represent the proportions of TZs observed after the remodeling period -E15 (HH41)-E19 (HH45)- whereas (E, F) represent the proportions of TZs observed during the remodeling period -E11 (HH37)-E14 (HH40)-. (D) Nasal RGC axons (N RGC) present a significantly lower proportion of TZs in the caudal area of EphA3ΔC-EGFP-overexpressed tecta between E15 and E19 whereas (C) temporal RGC axons (T RGC) do not present any significant difference in the rostral area of EphA3ΔC-EGFP-overexpressed tecta between E15 and E19 (Student t test, n: 6 EphA3ΔC-EGFP-overexpressed tecta versus 7 control tecta for nasal RGC; n: 4 EphA3ΔC-EGFP-overexpressed tecta versus 10 control tecta for temporal RGCs). (F) Nasal RGCs present a significantly lower proportion of TZs in the caudal area of EphA3ΔC-EGFP-overexpressed tecta between E11 and E14 whereas (E) temporal RGCs do not present any significant difference between the rostral areas of the EphA3ΔC-EGFP-overexpressed tecta and control tecta (Student t test; n: 6 EphA3ΔC-EGFP-overexpressed tecta versus 41 control tecta for nasal RGCs and 5 EphA3ΔC-EGFP-overexpressed tecta versus 53 control tecta for temporal RGCs). N: nasal, T: temporal, V: ventral, D: dorsal, R: rostral, C: caudal. Results are shown as mean +/− SE.