Fig. 4. Urethral defects in endodermal β-catenin LOF and GOF mutants. (A-F') Hematoxylin and Eosin (H&E) staining (A-F) and indirect immunoflouresence for E-cadherin (A'-F') on distal and proximal GTs. Note that in wild-type GT urethral cells form well-organized urethral plate distally (A,A') but remain as a tube at the proximal end (D,D'). In Shh^Cre/esr;β-Cat^c/c GT, urethral plate fails to form distally (B,B'), and the proximal urethra is open (E,E'). In Shh^Cre/esr;β-Cat^loxEx3 GT, disorganized distal urethral plate is formed (C,C'), and the proximal urethra showed severe endodermal overgrowth (F,F'). (A''-F'') Immunostaining confirms that β-catenin protein is removed from Shh^Cre/esr;β-Cat^c/c UE (arrowheads, B'',E'') and accumulates in Shh^Cre/esr;β-Cat^loxEx3 UE (C'',F''). (A'''-F''') Immunostaining showing K14 expression was detected in both surface epithelium and UE in wild-type GTs (A''',D'''). The expression is maintained in LOF urethra (B''',E''') but is repressed in cells with high β-catenin expression in GOF urethra (C''',F'''). Scale bars: 100 µm; 200 µm in insets.