Fig 2.

Rapid microbial induction of angiogenesis in small intestinal villi of adult ex-germ-free mice. (A–C) Confocal scans of the capillary network present in the upper third of small intestinal villi. Whole mounts are from the junction between the middle and distal thirds of the small intestines of 6-week-old NMRI mice (capillaries, green; nuclei, red). (A) Germ-free (GF) mouse. (B) Age-matched ex-germ-free conventionalized (CONV) mouse killed 10 days after colonization with an unfractionated microbiota harvested from a conventionally raised “donor.” (C) Ex-germ-free mouse 10 days after colonization with B. thetaiotaomicron (B. theta) alone. To view three-dimensional rotating images of the capillary networks shown in A–C, see Movies 3–5, which are published as supporting information on the PNAS web site, or go to http://gordonlab.wustl.edu/vasculature. (D) Quantitation of villus capillary network density. Mean values ± SEM are plotted for each condition. The asterisk indicates that the difference relative to germ-free mice is statistically significant (P < 0.005 according to Student's t test). (Bars in A–C, 25 μm.)