Evidence of induction of new nephrons in immature kidneys undergoing hypertrophy.

Unilateral nephrectomy performed during the first days or weeks of life may or may not induce the development of new nephrons in the remaining kidney. Such an increase has been reported to occur, as discussed in this review, in newborn rats and mice, but not in guinea pigs. These observations are consistent with other data suggesting different patterns of compensatory adaptation in young and in old animals.