Though the initial sequence of events following uninephrectomy in adult and infant rats is identical, the infant kidney is capable of generating new DNA while the adult kidney is not. In both infant and adult there is an increase in protein and protein:DNA ratio within 12 hours of uninephrectomy. Unlike the adult, however, the DNA content of the renoprival (remaining kidney after the removal of its partner) infant kidney is significantly elevated at 24 hours. This pure hyperplasia persists for at least seven days. By 14 days there is a small but significant rise in the protein:DNA ratio which increases considerably by 40 days. Thus, the renoprival infant kidney undergoes a series of changes with time beginning with pure hyperplasia and ending with nearly pure hypertrophy.
Karp R, Brasel JA, Winick M. Compensatory Kidney Growth After Uninephrectomy in Adult and Infant Rats. Am J Dis Child. 1971;121(2):186-188. doi:10.1001/archpedi.1971.02100130140020