Expression of musculoskeletal tissue marker genes in the head of turtle embryos at stage 15. (A) Lateral view of the head of a turtle embryo at stage 15. (B-F) Frontal sections prepared around the plane indicated by the red line in (A). (G-I) Frontal sections prepared around the plane indicated by the blue line in (A). (B, G)Runx2-positive mesenchymal cells (arrows) are broadly distributed at lateral portion of the head, from the top of the head to the ventral margin of the first pharyngeal arch. (C and H) Cranial muscular tissues are clearly labeled by MyoD probe. (D and I) Cartilaginous tissues, including the braincase and quadrate, are clearly labeled by Sox9 probe. (E)Scx is expressed in tendon primordia accompanying cranial muscles (arrowheads). (F)Six2 is expressed mainly in connective tissue cells associated with the braincase cartilage and jaw adductor muscle (arrowheads). Note that the anlage of jaw adductor muscle (red outlined domain) is covered by a thick layer of Runx2-positive mesenchyme laterally. Scale bar in (A) is 1 mm. Scale bars in (B-I) are 0.5 mm.
Tokita et al. SpringerPlus 2013 2:336 doi:10.1186/2193-1801-2-336