Expression of Wnt and Frizzled mRNAs in lenses cultured with TGFβ. (A) By 5 days culture with TGFβ2 rat lenses develop anterior subcapsular opacities, whereas in the absence of TGFβ, lenses remain transparent. (B) RT-PCR shows that capsule preparations (containing the lens epithelium and associated plaques) from lenses cultured with TGFβ2 express mRNA for Wnts 5a, 5b, 7b, 8a and 8b much more strongly than lenses cultured without TGFβ2. HPRT is used as a loading control. Of all the Wnts studied, Wnt 7a is the only isoform that is not upregulated by TGFβ2. (C) Histological sections that include the anterior pole of the lens show detail of plaques similar to those evident in (A). Representative images from an in situ hybridization analysis show that all the Wnts studied (with the exception of Wnt 7a) are all more strongly expressed in the subcapsular plaques of lenses cultured with TGFβ2 than in the epithelium of lenses cultured without TGFβ2. Expression of Frizzled 2 is also upregulated in the presence of TGFβ. Abbreviations: Fz2, Frizzled 2. Scale bar: A, 370 μm; C, 45 μm.