Mitotic behaviour and proliferative metabolism in allogenic rat kidney transplants in the first 6 days after recirculation

Comparative experiments were performed on 41 allogenic rat kidney transplants to determine the mitotic behaviour and proliferative metabolism (application of 3H-thymidine) in the first 6 days after recirculation. Three days after transplantation, DNA synthesis in the tubular epithelial cells of the cortex and the medulla reached its peak. After this time the 3H-thymidine labelling index for these cell nuclei dropped. On the 6th day, the value was equal to that of the first day. The following points are signs of rapid transplant rejection. It was predicted that the DNA synthesis in the epithelial cell nuclei would decline, and also that the lymphocytes would proliferate in the interstitial tissue of the transplant's cortex and medulla. From the 4th day on, these changes were observed. The changes in the proliferative metabolism of the tubular epithelial cell nuclei preceded the mitotic changes by a few hr. The transplant changes caused by ischemia followed by tissue rejection can be made comprehensible by the determination of the average cell density of 3H-thymidine-labelled cortical, medullar, and tubular epithelial cells.