Early changes in limb buds of chick embryos after thalidomide treatment.

Since the first observations of hypoplastic and aplastic thalidomide deformities in infants (McBride, 1961; Lenz, 1962), the literature on this subject has grown to many hundreds of communications. Experimental investigations in almost all cases have been undertaken to show whether thalidomide and its metabolites have any teratogenic effects in experimental animals. Numerous review papers are available on this subject, e.g. Giroud, Tuchmann-Duplessis & Mercier-Parot (1962), Somers (1963), and Salzgeber & Wolff (1964). Chick embryos did not seem for some time to be suitable for experimental production of typical thalidomide deformities. However, Kemper (1962a, b), Yang, Yang & Liang (1962). Boylen, Home & Johnson (1963) and Leone (1963) have shown that thalidomide can produce a whole range of ectromelian deformities provided that it is introduced into the egg at a particular period of embryonic development. Certain controversy was created when Williamson, Blattner & Lutz (1963) demonstrated that certain insoluble and otherwise inert substances such as powdered glass, colloidal alumina and colloidal clay, when introduced into the amniotic cavity in chick embryos, caused thalidomide-like malformations. More recently, Salzgeber & Salaun (1963 a, b, 1965) established that thalidomide produces in the chick essentially the same kind of malformations as it does in human and rabbit embryos. The present report gives an account of an investigation of short-term changes in chick embryos treated with thalidomide. This approach, if successful, would help to elucidate the mode of action of thalidomide on limb primordia when they are in the sensitive period of development.