Representative CIN 1 staining patterns.

<p>Columns a-d: Four H&E stained CIN 1 specimens (a, b, d, HPV 16 positive; c, HPV 35 positive); row e-h: HPV <i>E6/E7</i> RNA CISH staining patterns; row i-l: <i>p16</i> mRNA CISH staining patterns; row m-p: p16^INK4a IHC staining patterns. The first specimen (a) may represent an early lesion displaying low-level HPV staining (e) mostly in the lower half of the lesion with occasional superficial cells showing diffusely stained nuclei (black arrows, e-h). <i>p16</i> mRNA signals were undetected. p16^INK4a staining was scored as negative. The second specimen (b) shows a productive phase HPV staining pattern as indicated by the abundant diffusely stained nuclei throughout the epithelial thickness (f). <i>p16</i> mRNA signals were barely detectable (j). p16^INK4a staining shows patchy positivity (n). Specimen c also shows a productive phase pattern of HPV expression (g). <i>p16</i> mRNA signals were detectable in the lower third of the epithelium (k) matching p16^INK4a IHC staining (o). Most CIN 1 lesions showed the staining patterns shown for specimens b, f, j, n and c, g, k, o. An exception to this staining trend was found in specimen d, which showed strong staining for HPV in the lower part of the lesion and occasional diffuse staining nuclei (h). <i>p16</i> mRNA signals were detectable in the lower epithelial layers and strong p16^INK4a staining was detected throughout the lesion; possibly, this specimen represents a CIN lesion entering into a transformative phase directly from CIN 1 morphology. All images were originally taken using a 20X objective lens. Scale bar: 50 µm.