Assays of thymic selection. Fetal thymus organ culture and in vitro thymocyte dulling assay.

The in vitro methods of FTOC and DP dulling assay have been useful for defining the structural ligand requirements for positive selection of thymocytes. Both techniques, but especially the latter, have restrictions on their interpretation, which are outlined in the notes. The ability to study a cellular process in vitro has been, and will continue to be, of critical importance for immunologists. However, one should always be careful to confirm a hypothesis using in vivo techniques, whenever possible.