Figure 3
Digital pattern of the forelimb of emu adults and embryos. (a–c) Three-dimensional rendering from CT images of the digital plate of adult emu forelimb skeletons (left; ventral view) and their transverse sections taken from the limb at the level of the dashed line (right). Arrowheads indicate the vestigial digit 4 (4*). Medullar cavities are seen in the vestigial digit 4. (c) A right limb flipped horizontally. Scale bars, 20 mm (left) and 10 mm (right). (d–f) Alcian blue staining of wings of emu embryos at stages 36 (d), 37 (e) and 40 (f). Note that individual variation was recognised in the cartilage pattern of developing forelimbs (stage 36, n = 4; stage 37, n = 3; stage 40, n = 3). Left wings flipped horizontally. 2−4, digits 2−4; 2*, 4*, rudiment of digit 2 and 4, respectively. Scale bars, 2 mm.
