Thymic microenvironments, 3-D versus 2-D?

Lympho-stromal interactions in the thymus crucially determine the fate of d eveloping T cells. Epithelial cells, inter-digitating reticular cells, macr ophages and fibroblasts all play a role in the shaping of the T cell repert oire. Recently published evidence shows that lympho-stromal interaction act s bi-directional. Developing T cell themselves, at different stages of diff erentiation, control the microarchitecture of thymic microenvironments, a p henomenon designated as 'crosstalk: This paper reviews experiments showing that developing T cells crosstalk to different thymic epithelial cells in a stepwise fashion. In this way, correctly organized thymic microenvironment s guarantee normal thymopoiesis.