Figure 4

Meis2 transcripts are detectable in the distal autopod domain in mouse and bat limbs. During early limb development in the mouse, the 3′-Meis2 WISH probe detects expression in the proximal region of the limb bud (black arrow, A, B). A similar pattern can be seen in equivalently staged bat limbs (black arrow, C, D) and is comparable between forelimbs (FLs) and hindlimbs (HLs). During the early stage of mouse autopod development, Meis2 is not seen in the FL (E), but a small, comma-shaped domain of expression can be found in the HL (F) with this probe. In contrast to this, expression is found in the region between digits IV and V of the bat FL (G) and is absent in the HL (H). At later stages of digit formation, Meis2 can be seen in all of the interdigital regions of both the FL (I) and the HL (J) of the mouse and the FL of the bat (K) but is still absent from the bat HL (L). In the mouse, expression is restricted to the proximal region of the regressing interdigital mesenchyme (I, J, M and N) but is maintained in the webbing of the bat FL (O) while a very faint stripe of expression can be seen in the HL interdigital region (P). It is notable that Meis2 expression can be found in the FL and HL patagia throughout their development (red arrow in G, H, K, L, O, P). Dorsal views of autopods are shown. Scale bars represent 500 μm.