Figure 1 : Differentiation in non-renewing versus self-renewing tissues.

From: Hierarchical tissue organization as a general mechanism to limit the accumulation of somatic mutations

Figure 1

(a) To produce N mature cells from a single precursor with a minimum number of cell divisions, log2(N), strict division along a perfect binary tree is necessary. In multicellular organisms such ‘non-renewable’ differentiation typically takes place early in development. (b) However, in self-renewing tissues, where homoeostasis requires a continuous supply of cells, a small population of self-replicating tissue-specific stem cells sustain a hierarchy of progressively differentiated and larger populations of cell types, with cells of each type being continuously present in the tissue.