Figure 3.

Complementary patterns of NRG expression and distribution of ErbB4-expressing INs at E14.5 in WT mice are degraded in ErbB4-deficient mice. (A-F) In situ hybridization on coronal sections at two different levels ((A-C) anterior; (D-F) more posterior) as in Figure 1 but at E14.5; (C, F) merged images shown in (A, B), and (D, E), respectively. (A, D) In WT, migrating, ErbB4-expressing INs derived from the MGE are detected in the vTel and in their tangential migratory streams in cortex in the marginal zone (MZ) and intermediate zone (IZ) (arrows). (B) Nrg3 is expressed robustly in the cortical plate. (E) Nrg1-type III is highly expressed in the mantle zone of the vTel and in the VZ/SVZ in the dorsal telencephalon. (C, F) ErbB4-expressing INs are preferentially distributed within domains with low or undetectable levels of NRG expression. (G-I)In situ hybridization on coronal sections through forebrain of E14.5 ErbB4-/- HER4^heart mice for expression of ErbB4, marking primarily INs generated in the MGE and migrating to the cortex, and the neuregulin Nrg1-type III; (I) merged images shown in (G, H). Compared to their WT littermates (D-F), the distributions of the migrating ErbB4-expressing, MGE-derived INs is much broader and diffuse, exhibiting abnormally extensive overlap with the expression domains of Nrg1-type III (G-I). Arrowheads mark matching sites on the pair of sections (G-I). CTX, cerebral cortex; LGE, lateral ganglionic eminence; MGE, medial ganglionic eminence. Scale bar: 500 μm.