Dna synthesis in the urinary-tract epithelium of the rat induced by laparotomy and by intraperitoneal injection of distilled water, physiological saline and lycopodium spores.

The tritiated thymidine labelling index (LI) of the epithelium of the ureters and urinary bladder of young male Wistar rats is substantially increased 18 h after a simple laparotomy incision. A similar highly significant increase (P less than 0.001) has been observed after a single i.p. injection of various materials, including (a) distilled water, (b) 0.5% glycogen in physiological saline, and (c) 1% suspension of lycopodium spores in physiological saline. In each instance an aseptic inflammatory response develops in the peritoneal cavity. Reasons are given supporting the concept that a mitogen is produced from a constituent of the inflammatory exudate in the peritoneal cavity and that the factor reaches the affected epithelium by direct diffusion.