[Physiologic regeneration of rat urothelium after pulse and continual labeling with 3H-thymidine at various ages].

We investigated the physiological regeneration and the growth fraction of the growth fraction of the urothel in pyelon, ureter and urinary bladder from rats. The rate physiological regeneration was assessed with a single intraperitoneal doses of 37 KBq 3H-Thymidin/g body weight and the growth fraction with multiple administrations of the same doses over the time of 4 days. The age of the rats ranged from 60, 100 and to 165 days. The labelling index in the urothel was highest at the age of 60 days and yielded a ratio of approximately 0.6% in ureter, in pyelon approximately 0.35% and in the urinary bladder approximately 0.1%. The highest level labelling index was found within the bladder in the medial region and the lowest in the top third. The size of growth fraction in the animals in age of 60 days demonstrated in ureter approximately 6%, in pyelon approximately 3% and in the urinary bladder approximately 1%. The growth fraction of urothel, e.g. ureter, demonstrated a large difference between the basal (approximately 10%) and suprabasal cells (approximately 3%) in animals with on age from 60 days.