Fig. 6. Expression of axonal guidance molecules. Embryos infected at E3 were analyzed at either E6 (A,B,I-T) or E8 (C-H). (A-D) Expression of agrin (A,B) and chondroitin sulfate proteoglycan (C,D). No differences were observed between alkaline phosphatase- (A,C) and noggin- (B,D) infected embryos. (E-H) R-cadherin immunoreactivity. R-cadherin appeared localized to the pecten, optic nerve head and adjacent RPE in alkaline phosphatase-infected embryos (E,F), but was present in a much wider and more diffuse region in noggin-infected eyes (G,H). (I-P) Netrin immunoreactivity. Signals were localized to the optic nerve and ventral region of the presumptive ciliary body of alkaline phosphatase controls (I-L), but encompassed the entire ventral retina and secondary neuroepithelium of noggin-infected eyes (M-P). (Q-T) Netrin 1 mRNA expression. Netrin 1-positive cells were localized to the optic stalk in both alkaline phosphatase- (Q) and noggin- (S) infected embryos, but the latter also showed positive cells in the secondary neuroepithelium (arrows, T). AP, alkaline phosphatase infected; Nog, noggin infected; CSPG, chondroitan sulfate proteoglycan; IHC, immunohistochemistry; ISH, in situ hybridization. Scale bars: A-D, 50 µm; F,H, 100 µm; E,G, 500 µm; I,M, 500 µm; J-L, N-P, 50 µm; Q-T, 50 µm.