Analysis of Embryonic Cartilage and Bone Induction in a Defined Culture System

The primary means by which vertebrate mineralized tissues become determined during development is by interaction between different regions of the embryo, a process known as embryonic induction. Numerous examples of embryonic induction were intensively studied problems in developmental biology during the first 70 years of the 20th century (see reviews by Spemann, 1938, Grobstein, 1967; Hall, 1988). Progress in the last few years has in part been the result of applications of recombinant DNA technology to classical questions in the field of embryonic induction (e.g. see recent reviews by Gurdon, 1987; 1988; Edelman, 1988). The key issues appear to be when, where and which sequence of regulatory factor expression activate signal transduction processes resulting in the allocation, determination and differentiation of specific phenotypes. There are probably multiple signals and multiple receptors required for inductive processes.