Figure 2.

In vivo lineage tracing in the small intestine. (A) Stem cells exclusively express GFP and the inactive version of Cre. (B) On activation of Cre, LacZ can be transcribed. (C) After cells differentiate, the GFP and inducible Cre are no longer produced. LacZ expression will be maintained. (D) In vivo small intestinal crypt of Lgr5-EGFP-Ires-CreERT2 mouse with all of the above scenarios. (E) Cartoon of small intestine in which lineage tracings (blue) are visualized at different stages originating from LGR5⁺ISCs (green; Barker et al, 2007). Over time, true stem cells generate clones that are long-lived (self-renewal) and contain different cell types (multipotency). The crypt to the right shows lineage tracing with R26R-Confetti in which stem cells, and subsequently their progeny, are marked with different colours (Snippert et al, 2010b). EGFP, enhanced green fluorescent protein; GFP, green fluorescent protein; ISC, intestinal stem cell; LGR5, leucine-rich repeat-containing G protein coupled receptor 5.