Thymus development and function.

Thymopoiesis is a complex and highly dynamic process. It involves reciprocal tissue interactions between epithelial cells derived from the endoderm of the anterior foregut and neural crest-derived mesenchyme to form the thymic rudiment. This organ anlage attracts thymocyte progenitors and supports their differentiation and functional maturation into a self-tolerant diverse repertoire of T cells. In recent years, a more detailed picture of the molecular mechanisms determining the formation of the thymic rudiment and those controlling the maturation of the epithelial compartment has emerged and these are briefly summarized here. This review also addresses new experimental approaches toward a better understanding of thymopoiesis and discusses the impact of new animal models.