Before revision: The identifcation and separation of intrinsic variability from age-related phenomena has been the subject of a growing body of literature, supporting renewed interest in traditional analytic methodologies including use of the  von Foerster equation  for predicting population growth and cell age distributions.
After revision: Many single-cell observables are highly heterogeneous. A part of this heterogeneity stems from age-related phenomena has been the subject of a growing body of literature, supporting renewed interest in traditional analytic methodologies including use of the von Foerster equation for predicting population growth and cell age distributions.