The cycling activity of CRUs is downregulated between 3 and 4 weeks of age.
Shown are the number of CRUs per 105 initial total viable cells. FL cells were depleted of Ter119+ cells; for the 3- and 4-wk BM cells, all lin+ cells except Mac1+ cells were removed; and for the 10-wk BM cells, all lin+ cells including Mac1+ cells were removed. Values are mean ± SEM from data pooled from at least 3 experiments per tissue. **