Fig. 6. Distal small intestinal epithelium extends toward an FGF10, but not an FGF9, source. BSA-, FGF9- or FGF10-soaked beads were placed in Matrigel two-bead diameters from a wild-type distal intestinal epithelial explant in which mesenchymal tissue had been removed. (A-D) Intestinal epithelium did not grow when exposed to a BSA-soaked control bead over an 84-hour period. (E-H) In response to an FGF9 bead, intestinal epithelium showed a modest dilation but no directional extension towards the bead. (I-L) In response to an FGF10 bead, intestinal epithelium showed a significant dilation and extension towards the bead.