Figure 9.

Plasticity between Lgr5 and Bmi1 expression states under ex vivo 3D culture. Single Lgr5⁺ ISCs undergo dynamic transition between stem states (Lgr5^GFP-expressing [green], Bmi1^GFP-expressing [blue]) over the course of 3D culture generation. Lgr5^GFP ISCs first generate small spheroids that down-regulate Lgr5-GFP reporter expression, but begin to express Bmi1^GFP. Next, as crypt-like buds begin to form, the Lgr5^GFP is up-regulated at the site of emerging crypt domains in conjunction with formation of granular Paneth cells. Finally, the mature Rspo1-dependent enteroid structure forms, containing differentiated regions (gray), and retains Lgr5^GFP expression localized within the ends of the crypt bud domains.