Fig. 5. The D-V lineage restriction boundary correlates with the Lmx1b expression domain. (A-C) Immunodetection of Lmx1b protein. (A) An E13.5 autopod sectioned transversally. Arrowheads indicate the sites of chondrogenic condensation. (B) A transversal section of an E13.5 mouse limb at the level of the digital prechondrogenic condensations (circles). (C) A longitudinal section of the undifferentiated digit tip at E13.5. (D-I) Immunodetections on E11.5 limbs. (E,G,I) Lmx1b expression, together with the distribution of GFP-positive cells. (D,F,H) The same fields as in E, G and I, respectively, but excluding the GFP channel to reveal Lmx1b expression in clone cells (arowheads). D and E show in detail the distribution of cells belonging to a dorsal clone in relationship to the Lmx1b D-V boundary. Low-(F,G) and high-magnification (H,I) views showing the distribution of cells belonging to a ventral clone in relationship to the Lmx1b D-V boundary.