Thymic epithelial cells derived from the cultures of thymic nurse cells.

Thymic epithelial cells are derived from the cultures of thymic nurse cells. These cultures are free from fibroblasts and macrophages. The epithelial nature of these cells is confirmed by demonstrating the presence of keratin filaments in them. These epithelial cells show heterogeneity in shape, size and distribution of keratin filaments. They contain nonspecific esterase(s) molecules and express both I-A and H-2K antigens.