Thymus Ontogeny and Development

Abstract

The thymus is a primary lymphoid organ constituted by a 3D epithelial network that provides a specialized microenvironment in which seeding lymphoid progenitors undergo phenotypical and functional maturation. During the earlier steps of thymic organogenesis, the specification of the pharyngeal endoderm to thymus fate takes place independently of the expression of the transcription factor Foxn1 that, however, governs the later organogenesis of thymus together with the colonizing lymphoid cells. In the present chapter, we will review evidence describing early development of thymus and its resemblance with the development of endoderm-derived epithelial organs based on tubulogenesis and branching morphogenesis as well as the molecules known to be involved in these processes.Este capítulo de libro revisa los procesos de especificación del epitelio tímico inducidos por Foxn1 en el endodermo común de la tercera bolsa faríngea, el fenómeno de la tubulogénesis y el branching de dicho primordio y las moléculas implicadas en tales procesos así como el papel de los progenitores linfoides que colonizan el primordio tímico durante el desarrollo