Figure 3 in Development and variation of the anuran webbed feet (Amphibia, Anura)

Figure 3. Early differentiation of the primary cartilaginous condensations of metatarsals among selected anurans. A–C, Chacophrys pierottii, larval stages 35, 37 and 39. Proximo-distal elongation of digit IV (metatarsal and phalanges) is always advanced with respect to development of the others digits. D–F, Pseudis paradoxa, larval stages 32, 35 and 37. Differentiation of metatarsal IV and that of metatarsal III occur simultaneously. Metatarsals are quite similar in length. G–I, Xenopus laevis, larval stages 34, 36 and 40. Primary cartilages of metatarsals IV and III are the first to differentiate but are as long as metatarsals V and II, which appear subsequently. Scale bar = 0.2 mm in A, D–I, and 0.5 mm in B, C, F. Abbreviations: V, metatarsal V; IV, metatarsal IV; III, metatarsal III; II, metatarsal II; I, metatarsal I; Ph, prehallux.