Erythematous ears and blood-filled dermal lymphatics in kCYC^+/- transgenic mice. (A) Erythematous ear 1 week after tagging in a TG (left), but not WT (right), mouse. (B) H and E staining of skin from tagged ears showing extravasated erythrocytes and erythrocytes filling vascular structures in TG (left), but not in WT (right), skin (× 100). (C) Whole-mount visualization of an unstained tagged TG mouse ear showing blood within (arrows) and outside of (arrowheads) vascular structures. (D) Whole-mount visualization of a tagged TG ear by light (left) and immunofluorescence (right, podoplanin staining in green) microscopy showing lymphatics filled with blood. (E) Antipodoplanin (red) and H and E staining on serial sections of a tagged TG ear showing dilated lymphatics filled with erythrocytes (arrows) (× 40). (F) Anti-CD31 (green) and antipodoplanin (red) staining of tagged TG ear showing that dilated vessels are CD31 dimly positive and podoplanin positive (arrows), which is consistent with a lymphatic phenotype. By contrast, the nondilated blood vessels are CD31⁺ and podoplanin negative (arrowheads) (× 40).