Fig. 3. Deregulation of Notch signaling molecules in COUP-TFI^-/- cochlea. (A-C') In situ hybridization on sections of wild-type (A-D,I-L,Q-R,V-Y) and COUP-TFI^-/- (E-H,M-P,T,U,Z-C') cochlea for Jag1 (A-H), Hes5 (I-P), and Lfng (Q,R,T-C'). (A-D) At E15.5, Jag1 in wild type was predominately expressed in the region where the non-sensory cells (arrow) are differentiating. (E-H) In COUP-TFI^-/- cochlea, there was a lack of upregulation of Jag1 in the supporting cells region. (I-P) Hes5 expression in wild type (I-L) was restricted to the Deiter's supporting cells (SC) of the sensory epithelium, whereas in COUP-TFI^-/- mutants (M-P), Hes5 expression was downregulated. (Q,R,T-C') At E14.5, there was a dramatic expansion in the Lfng expression domain (compare R and U, circles); at E15.5, expansion to the greater epithelial ridge (GER) was observed only in the wild type (W-Y), whereas expansion to the lesser epithelial ridge (LER) was also observed in COUP-TFI^-/- mutants (A'-C'). (S) Immunofluorescence staining of COUP-TFI (-COUP-TFI) in wild-type sensory epithelium at E14.5 (arrowhead marks a hair cell). Scale bar: in A,E,I,M,Q,T,V,Z, 200 µm; in B-D,F-H,J-L,N-P,R,S,U,W-Y,A'-C', 50 µm.