Is TCR beta expression an essential event in early thymocyte development?

The evolution of a T cell through the thymus is characterized by several distinct morphological changes. The underlying mechanisms allowing a double negative thymocyte to mature to a double positive one expressing both CD4 and CD8 are still hazy. Here, Donald Palmer, Adrian Hayday and Michael Owen discuss the latest development in the field and data that underscore the crucial role of TCR components in the transition of double negative to double positive thymocytes.