RNAscope was performed using the RED2.5 detection system, imaged with confocal microscopy and pseudo-colored pink to provide maximal contrast. (A-C) Low magnification images of full forelimb zeugopod at E15.5 and expression of Hox11 paralogous group genes. Hoxa11 (A) displays the broadest expression profile and is highly expressed in the distal zeugopod surrounding and including the developing distal growth plates. Hoxd11 (B) displays a more posteriorly restricted profile surrounding but excluded from the developing distal growth plates and extending further into the proximal olecranon. Hoxc11 (C) is not expressed in the forelimb. (D-G) Expression of Hoxa11 and Hoxd11 in newborn zeugopod joints. Hoxa11 (D) is highly and broadly expressed in all elements of the newborn wrist while Hoxd11 (E) is restricted to the posterior wrist elements. Hoxa11 and Hoxd11 are both minimally expressed in the elbow at newborn stages (F-G). (H-K) In the adult wrist joint, Hoxa11 is maintained in both the cartilage (H) and synovial lining (J). Hoxd11 is not expressed in articular cartilage (I) and displays low expression in the synovial lining (K). Dashed lines denote approximate boundaries of the tidemark. r, radius; u, ulna; h, humerus; ha; hamate; cap, capitate; tr, trapezoid; lu, lunate; sc, scaphoid; ole, olecrenon. scale bars: A-G = 500 μm; H-K = 50 μm.