Fig. 3

Topological relation of the protrusion with muscle and tendon. a–d, Muscles and bones in the hindlimb feet of X. tropicalis (a, b) and X. laevis (c, d). Arrowheads indicate the protrusion (a) and prehallux (c). ip: interphalangei, fa: flexor accessories. (b) and (d) are high magnification images of those in (a) and (c), respectively. e, f, A tendon was connected to the distal protrusion of X. tropicalis (e) and the distal phalanx (digit III) (f) (arrows). f: forceps for highlighting the tendon. Images in (a–e) are ventral views, and (f) is a posterior view. Scale bars: 1 mm in (a, c) and 500 μm in (e, f)