Minireview: Intrinsic and extrinsic factors in thyroid gland development: an update.

In vertebrates the portion of the thyroid gland synthesizing the thyroid hormones develops from a small group of endodermal cells in the foregut. The nature of the signals that lead to the biochemical and morphogenetic events responsible for the organization of these cells into the adult thyroid gland has only recently become evident. In this review we summarize recent developments in the understanding of these processes, derived from evidence collected in several organisms.