Figure 4. Paneth cells regulate numbers of intestinal stem cells in vivo.

a-k: Paneth cells and stem cells in constitutive models of Paneth cell decrease. a-c: lysozyme stain (brown arrowheads indicate positive cells) and d-f: Olfm4 staining of crypts of adult (6-7 week-old) mice of the indicated genotypes. g-j: double stain, lysozyme (brown), Olfm4 (blue) of a representative crypt of the indicated genotype. Brown and blue arrowheads indicate Paneth cells and stem cells, respectively. k: Quantification of stem and Paneth cell numbers in both models. For each bar, 100 crypts were scored for each of three mice. Mutant mice (red) and their control mice (blue). *: p<0.01. l-t: Paneth cells and stem cells in inducible Paneth cells depletion model. Mice indicated genotypes were injected with β-napthoflavone to induce Cre and were analyzed 54 or 67 days after Cre induction by staining for Sox9 protein (brown), Olfm4 or Cryptdin mRNA (blue). Serial sections: i,o,r; m,p,s; and n,q,t. See text for experimental detail. Note the absence of Paneth cells (s) and stem cells (p) in Sox9-/- crypts (m). Scale bar: 50 μm