Cytopathological effect of partial cystectomy of rats.

The effect of partial cystectomy on induction of DNA synthesis in the urinary bladder epithelium was studied in a total of 147 male F344 rats. DNA synthesis started 12 hours after 75% or 50% resection of the bladder, and reached a maximum at 48 hours with a mean labelling index of 15.8% after 75% partial cystectomy and 13.8% after 50% partial cystectomy. In these two groups the proliferative activity of bladder epithelial cells returned to normal after 2 weeks and 1 week, respectively. Cytodifferentiation of epithelial cells, observed by transmission and scanning electron microscopy, remained normal during the regeneration process.