Morphologic changes in rat urothelial cells during carcinogenesis: II. Image cytometry

Improved early detection of neoplasia by screening of urothelial cells requires an understanding of the features distinguishing normal and neoplastic cell populations. We have begun a program of study based upon a rat model system for the controlled observation of early‐stage lesions produced by the carcinogen N‐butyl‐N‐(4‐hydroxybutyl)‐ nitrosamine. Cells dissociated directly from normal and malignant urothelium were characterized by conventional cytopathology techniques and by quantitative microscopy (for nuclear texture and nuclear and cytoplasmic size, shape, and stain content) to derive a comprehensive picture of bladder tumor development. By following the changes that occur in the dissociated urothelial cells we have found that the nuclear area, total nuclear stain, nuclear shape, and the nuclear chromatin change significantly over a 48‐wk interval as the lesions progress toward malignancy.