In vitro models of T cell development.

A number of in vitro systems are currently being used to study both thymocyte development and thymic stromal cell function. However, the usefulness of dispersed culture systems is limited since they often involve disruption of interactions within the normal three-dimensional architecture of the thymus in vivo which are critical for normal development to proceed. In contrast, Fetal Thymus Organ Culture (FTOC) provides an experimental system where such interactions are maintained, thereby allowing in vitro access to key aspects of thymocyte development. More recently, Reaggregate Thymus Organ Cultures (RTOCs) have allowed detailed analysis of thymic stromal cell function, while retroviral transfection of thymocyte subsets under FTOC conditions provides a rapid means to investigate thymocyte development at the molecular level. Current use of the FTOC approach is summarised here, and where appropriate is compared to the use of dispersed culture systems. Copyright 1999 Academic Press.