Figure 1.

The tree-like structure of haematopoiesis. Haematopoiesis exhibits a hierarchical architecture so characteristic of general body tissues. At the root of this tree-like structure, one finds the tissue-specific stem cells, which can self-renew (reproduction) and differentiate into all other types of haematopoietic cells. The figure illustrates specifically the most common haematopoietic cell types, from progenitors to mature cells. Along this path of differentiation, we also find the so-called precursor cells. In the mathematical model of haematopoiesis referred to in the main text, cell reproduction and differentiation constitutes a coupled stochastic event, occurring with probability 1 − ɛ and ɛ, respectively, as illustrated on the right.