Abstract
Regeneration of the heterotopically transplanted bladder (HTB) was histologically evaluated in a total of 30 rats sacrificed on days 3, 7, 14, 28, 42, and 56 after transplantation. The mucosa underwent severe necrosis and inflammatory change by day 3, but by 7 days regeneration occurred and was accompanied by simple hyperplasia and even papillary or nodular hyperplasia by 28 days. Regeneration gradually subsided, and by 56 days the mucosa and submucosa were nearly normal. 5-bromo-2'-deoxyuridine labeling indices correlated with the histologic changes observed in the regenerative process. The values reached a maximum by 28 days (1.9%), and then decreased. The generative process in the HTB differed from cyclophosphamide-induced cystitis of the homotopic (non-transplant-ed) bladder. It is concluded that considering the mucosal regenerative process of the HTB, 4 weeks after transplantation seems to be the proper period for instillation of test chemicals to be started.
