Figure 2.

SC specification and differentiation in intestinal COMs. (A) Intrinsic regulation as suggested by Almet et al. [22]. Two types of cells (SC: stem cell (soft), PC: Paneth cell (hard)) divide asymmetric or symmetric with a defined probability p Є [0, 1]. (B,C) Environmentally regulated fate: (B) Detailed scheme provided by Pin et al. [16,21]. Dividing SCs self-maintain or irreversibly specify into absorptive or secretory cells/progenitors depending on externally provided Wnt and Notch signaling. Further specification into different secretory cells is controlled by the probabilities p and q that are Wnt-dependent. SeC: secretory cell, GC: goblet cell, TC: tuft cell, EE: enteroendocrine cell, pEC: enterocyte progenitor, EC: enterocyte. (C) Tissue shape-dependent regulation [20]. Fully reversible lineage specification is linked to Wnt and Notch signaling. PC specification in addition requires a threshold tissue curvature: C > 1/R₀. R₀: local curvature radius of the tissue.