Connexin expression in normal and dysplastic human cervical epithelium. All nuclei are stained with DAPI (blue). A: All normal ectocervical tissue sections revealed positive staining of connexin43 gap junctions (red) particularly in the spinous layers. Connexin26 was also positive (green), particularly in upper spinous and more superficial layers. Overlapping expression of connexin43 and connexin26 was observed (yellow) and these areas displayed particularly large gap junction plaques (arrow). B: Connexin30 (red) displayed a similar staining pattern to Connexin26 although gap junction plaques were more frequently observed in lower spinous layers (arrow). In these normal sections, the proliferation marker Ki-67 was detected (turquoise) in basal and immediate suprabasal layers only, as expected. (C) In all premalignant CIN III sections there was complete absence of connexin26 (green) and connexin30 (red). D: In one CIN III lesion, small amounts of connexin43 (red) were present, mainly as diffuse cytoplasmic staining, but no positive connexin26 staining was detectable (green). E: In CIN I/II lesions no clear connexin26 gap junctions were present (green) whereas several connexin43 plaques were visible (arrow), but in a less homogenous fashion compared to normal ectocervix. F: Connexin30 gap junctions were clearly detected in areas of low grade CIN I lesions, although they tended to occur in stratified regions of cell differentiation (arrow) rather than areas of abnormal cellular proliferation (Ki-67, turquoise) and atypical cellular crowding.