Figure 6

mRNA wholemount in situ hybridisation expression of HOXA13 (A) and HOXD13 (B) in the tammar forelimb and hindlimb from day 18 to day 24.5 of pregnancy. The top images for each gene are forelimbs with the corresponding hindlimb in the lower panel. Expression was first visible at day 18.5 in the forelimb. HOXA13 was expressed in the interdigital regions of the autopod by day 21 of pregnancy. Hindlimb mRNA was detected in the distal region of the hindlimb at day 21. HOXD13 in the forelimb was expressed distally from day 18 and became interdigital in the forelimb by day 21.5 of pregnancy. In the hindlimb, HOXD13 mRNA was not detected at day18 and 19, but was weakly expressed in the distal region at day 21.5. By day 23.5 was expressed in the anterior and posterior points of the limb and after day 24 to encompass the distal end of the hindlimb and became interdigital by day 24.5. All images are dorsal and orientated to point distally (n = 3).