Notch1^-/-mice develop progressive corneal opacification and keratinization.

<p>In WT (A) and Notch1 heterozygotes (N1^+/-) mice (B) corneal examination does not show any change after 4-OHT treatment and stays normal while conditional Notch1^-/- mice at 6 weeks after tamoxifen injection, demonstrate early corneal stromal opacification (C-1) which later progressed to keratinization and secondary neovascularization (white arrow head) (C-2). By 8 weeks after treatment almost 92% of Notch1^-/- mice developed corneal opacification/keratinization, while none of the WT or Notch1^+/- group showed this phenotype (<i>P</i> < 0.0001) (D). Wild type mouse corneal section showing normal histology on H&E staining (E) with no evidence of keratin 10 by immunostaining (F). On H&E staining, corneal lesions in Notch1^-/- mice demonstrate significant stromal infiltration (asterisk) with areas of keratinization and ulceration (black arrows) (G, H). The expression of keratin 10 (green) in the metaplastic epithelium confirms the skin-like epithelial phenotype (I). Green: FITC, Blue: DAPI; Scale bar: 50 µm.