Endosialin expression patterns in stage E14.5 and E17.5 mouse tissues. Global pattern of endosialin expression in an E14.5 embryo (A), in the lung (B) and in the eye cup (C) at the same stage. In a parasagittal section (A), endosialin is seen in mesenchymal cells in the head and in the pelvic regions, in particular in organs of the genitourinary system. In the developing lung (B) and eye (C), endosialin is found at the epithelial-mesenchymal interface of developing lung buds and under the epidermal invagination of the skin during the development of the optic cup (arrows). In the stomach of a E17.5 embryo (D; gastric lumen marked St), endosialin is found in mesenchymal cells of the lamina propia; in the same panel (D) endosialin expression is also visible in the subcutaneous tissue of the skin, and in the perimysium of the intercostal muscles. In the kidney (E), endosialin maps chiefly to the immature glomeruli. In the lung (F, G), endosialin is not detectable (F), whereas αSMA (G) marks vascular smooth muscle (blood vessels marked BV) and myoepithelial cells around bronchial epithelium (marked B). Scale bars: 50 µm (B, C), 125 µm (D), 25 µm (E-G).