Proliferative activity in the kidneys of aging mice evaluated by PCNA/cyclin immunohistochemistry.

The change of proliferative activity in mouse kidney cortex cells due to aging was studied by PCNA/cyclin immunostaining. Mouse kidney tissues of various ages: late fetal, newborn, suckling, weaning, adult and senescent were used for this experiment. Small pieces of kidney tissues were fixed in methacarn solution and embedded in paraffin. Sections were stained with PCNA/cyclin monoclonal antibody. The reaction product for PCNA/cyclin was observed mainly on nuclei. The ratio of the PCNA/cyclin positive nuclei to the total number of nuclei were calculated. PCNA/cyclin positive ratios in glomeruli and uriniferous tubules in the superficial layer were higher than those in the deep layer from late fetal period to suckling period. They decreased due to aging after birth and became to nearly zero after weaning period.