A model for ulnar dysmelia.

The treatment of pregnant rats with the carbonic anhydrase inhibitor, acetazolamide, produced gross limb malformations primarily affecting the forepaw, but also producing variable ulnar dysmelia. Analysis of the cytoarchitecture of the ulnar dysmelic limbs showed the presence of cartilaginous and fibrocartilaginous connections between the ulnar and radial chondroepiphyses, with variable deformation of the radial chondroepiphysis by the tethering effect (although the growth plate, per se, did not appear affected at the stage of development studied). The extremely variable experimental appearances duplicated most of the variations seen in the human disease analogue, and suggest this drug-induced embryopathy may be useful as a model for the study of postaxial forelimb deformities in the postnatal phase in order to adequately assess the structural changes of disparate growth between radius and ulna due to the presence of the cellular continuity between the two distal chondroepiphyses.