Fig. 5.

(a) Ossification in forelimb seen by whole mount technique at 16.5dpp. Note ossification in phalanges (p) and metacarpals (mc). Carpus remains cartilaginous. Scale bar = 500 µm. (b) Opossum hindlimb at 16.5dpp. Note ossification in femur (fe), tibia (t), fibula (f) and phalanges (p). Scale bar = 500 µm. (c) Growth plate from forelimb long bone at 16.5dpp, stained by Masson's trichrome technique. r = resting zone of cartilage, p = zone of proliferation, h = zone of hypertrophy, c = zone of calcification of cartilage matrix. Note endochondral bone (arrow) in zone of ossification. Scale bar = 200 µm.