Thymic nurse cell (TNC) (mouse)

Electron microscopy. The thymic nurse cell (TNC) consists of an epithelial reticular cell (type II) enclosing thymocytes. The TNC exists as a sealed structure in situ, i.e. the lymphocytes within the TNC are isolated from the general thymic environment. TNC are located in the cortex, where mature thymocytes are rare. (1): thymocytes enclosed in the arms of a TNC cell possessing several nuclei (2). Background: The occurrence of mature phenotype cells as well as immature lymphocytes with low CD3 expression level, within these structures, suggests that they represent a microenvironment for the selection and generation of mature T cells. They express MHC, secrete hormones and cytokines. A single TNC, by providing specific microenvironments, might have different roles in T cell development: phagocyte activity; nursing activity; capability to stimulate proliferation of thymic T cells and probably mediating selection processes.