Increasing adipocyte number as the basis for perirenal depot growth in adult rats.

The mass of the perirenal adipose depot in male Fischer 344 rats increases between 6 and 18 months of age. This increase is due to an increase in the number of adipocytes in this depot, in contrast with the concept that adipocyte number is constant throughout adult life. The epididymal depot increases in mass between 6 and 18 months of age by adipocyte hypertrophy alone.