Establishment of an epithelial cell line from rat thymus.

A cell line (IT-26R21), composed only of epithelial cells, was established from normal rat thymus. Thymuses were treated with both collagenase and trypsin. Four months after the initiation of cultures, epithelial cells in packed colonies formed a monolayer and no other cells were found in cultures. Thereafter, epithelial cells have been subcultured with trypsin and EDTA, and are currently at the 30th subculture. Based upon the fine structure of the thymus in vivo, IT-26R21 cells were identified as epithelial cells from the thymus, because of their mosaic-like arrangement, desmosomes and tonofilaments. Other features also supported their origin and identity.