Low temperature fluorescence imaging of freeze-trapped human cervical tissues

We characterized the fluorescence intensity distribution within the epithelia and stroma of frozen human cervical tissues at the following excitation-emission wavelength pairs: 440, 525 nm and 365, 460 nm. The intensities at both excitation-emission wavelength pairs are significantly lower in the epithelia of severely dysplastic tissues, relative to that in normal and inflammatory tissues. Furthermore, there are small differences in (1) the epithelial intensity of severe dysplasia and mild dysplasia at 440, 525 nm and (2) the stromal intensity of inflammatory and severely dysplastic tissues at 365, 460 nm. A comparison of the ratio of intensities at 440, 525 nm and 365, 460 nm between the epithelia of each tissue type indicates that this ratio is lowest in severely dysplastic tissues. It is interesting to note that the epithelial and stromal intensities are comparable at 365, 460 nm; however, at 440, 525 nm, the epithelial intensity is more than a factor of two less that that of the stroma for all tissue types. (C) 2001 Optical Society of America.