Fig. 5. A–D, Late effects of N-cadherin blockage on tectal development. Sections through the tectum of an E10–E11 chicken embryo injected at E4 and E5 with control rat IgG (A) or with a monoclonal antibody against N-cadherin (B–D) are shown. Consecutive sections were stained for Nissl substance with thionine (Thio;A, B), hybridized in situwith cRNA probe for N-cadherin (N-cad;C), and immunostained with a monoclonal antibody against axonin-1 (ax-1; D). Note the additional layers between remnants of the ependymal lining (arrowsin B) and the ventricular surface of the NCD-2-injected brains. Small arrowheads in C point to large multipolar N-cadherin-expressing ganglion cells reminiscent of those normally found in layer IV (Redies et al., 1993). In the NCD-2-injected brains, cells with a similar appearance are present in an additional layer close to the ventricle (large arrowheads in C). Small arrowheads in D point to axonin-1 immunoreactivity reminiscent of that normally seen in layer III (Yamagata et al., 1995). Note that in addition, axonin-1 immunoreactivity can also be seen immediately below the ventricular surface of NCD-2-injected tecta (large arrowheads inD). The ventricular surface lacks an ependymal lining (large arrowheads in B).E–J, Late effects of N-cadherin blockage on the development of the dorsal thalamus. Frontal sections through the diencephalon from a noninjected E11 control embryo (E–G) and from an E10–E11 embryo injected with monoclonal antibody NCD-2 against N-cadherin (H–J) are shown. Consecutive sections were Nissl-stained with thionine (Thio;E, H), or immunostained with antibodies against cadherin-7 (cad7; F,I) and R-cadherin (R-cad;G, J). The arrow inG points to the border between the ventral thalamus (VT in E) and the dorsal thalamus (DT in E). This border is marked by the R-cadherin-positive zona limitans (zl inG) (Gänzler and Redies, 1995). The dorsal thalamus, but neither the habenular area of the epithalamus nor the ventral thalamus, is severely distorted by the antibodies against N-cadherin. Arrows in J point to remnants of the ependymal lining, which is missing from most of the ventricular surface of the dorsal thalamus. Note that in the NCD-2-injected brains, gray matter is fragmented and fused at the midline in the dorsal thalamus. Like parts of the dorsal thalamic complex (DCin F), some of the fragments express cadherin-7 and R-cadherin. d, Dorsal; HM, nucleus habenularis medialis; NE, neuroepithelium;SMe, stria medullaris; Tel, telencephalon; tV, tectal ventricle; v, ventral; v3, third ventricle; I-X, tectal layers at E10–E11 (LaVail and Cowan, 1971). Scale bars:D, 0.1 mm (A–D);J, 0.5 mm (E–J).