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. Author manuscript; available in PMC: 2008 May 2.
Published in final edited form as: Cell. 2006 Apr 7;125(1):127–142. doi: 10.1016/j.cell.2006.01.042

Figure 4. CRD-Nrg1 Is Expressed in MGE Corridor Cells and Contributes to TCA Pathfinding.

Figure 4

Serial coronal sections through the telencephalon of E13.5 embryos.

(A) CRD-Nrg1 expression in the striatum (Str) and in cells forming the medial ganglionic eminence (MGE) corridor (arrowhead).

(B) Islet1 expression in the Str and in cells forming the MGE corridor (arrowhead, bracket).

(C) Islet 1 and CRD-Nrg1 in MGE corridor cells (arrowhead, bracket). Double in situ image was composed from immediate adjacent sections using Adobe Photoshop software.

(D) ErbB4 expression in the dorsal thalamus (dTh).

(E) Experimental paradigm used to analyze the response of TCAs to CRD-Nrg1-transfected COS cell aggregates in slice cultures.

(F and I) DiI-labeled TCAs traveled normally through the telencephalon toward the neocortex (NCx) in controls (F) but derailed from their normal path (arrowhead in [I]) when they contact a COS cell aggregate expressing CRD-NRG1. Asterisks mark DiI placements in the dorsal thalamus (dTh).

(G and J) Higher magnifications of the images shown in (F) and (I), respectively.

(H and K) Schematic representation of the pathway taken by TCAs in response to control and CRD-Nrg1 transfected COS cell aggregates.

(L and P) Nuclear counterstain of CRD-Nrg1 heterozygous (L) and CRD-Nrg1 mutant (P) E14.5 coronal sections shows that TCAs abnormally defasciculate in the MGE corridor of mutants (open arrowheads and brackets in [P] and [Q]) compared to controls (arrowheads and brackets in [L] and [M]).

(M and Q) High magnifications of DiI-labeled axons in E14.5 CRD-Nrg1 heterozygous (M) and CRD-Nrg1 mutant (Q) showing that the MGE corridor is wider and more disorganized in CRD-Nrg1 mutants (arrowheads) than in control brains.

(N and R) High magnification of L1-labeled axons observed in the NCx of control (N) and CRD-Nrg1 mutants (R) at E14.5.

(O and S) Schematic representation of the pathway taken by TCAs in control and CRD-Nrg1 mutants. H, hippocampus; Hb, habenula; Hyp, hypothalamus; LGE, lateral ganglionic eminence; GP, globus pallidus; PCx, piriform cortex. Scale bars = 200 μm (A–D, H, L, J, and P), 1 μm (F and I), 300 μm (G and J), and 100 μm (M, N, Q, and R).