The teratogenic effects of 5-fluoro-2-desoxyuridine (F.U.D.R.) on the Wistar rat fetus with particular reference to cleft palate.

The teratogenic effects of 5-fluoro-2-desoxyuridine on Wistar rat fetuses were studied macroscopically, microscopically and ultrastructurally. In no case did palatal shelf elevation occur, and a palatal shelf elevating force could not be demonstrated in freshly-removed fetuses. The shelves, like the connective tissues generally, showed clear evidence of depressed mucopolysaccharide synthesis. The shelves eventually ossified in the vertical position, and in some cases their free edges fused with the lateral wall of the oral cavity (palato-oral fusion). The results were consistent with the mucopolysaccharide-turgor hypothesis advanced by the author in a previous paper to account for normal shelf elevation. Phocomelia, brain and limb bud haemorrhages, gross subcutaneous oedema, hyperextension of the cranial base, fused vertebrae, detached epithelia, bizarre brain abnormalities (including some remarkable attempts at neural reconstitution) and growth and ossification of the mandible in the virtual absence of Meckel's cartilages were also noted in these fetuses.