Myoid and epithelial cell differentiation in myasthenic thymuses.

This study demonstrates that the stromal thymus elements of postcapillary venules are the source of desmin-positive mesenchyme from which both myoid and epithelial cells arise. The double staining revealed various degrees of desmin and keratin positivity in the same kind of cells in the medulla as well as in Hassall's corpuscles. Hassall's corpuscles seem to arise from several kinds of cells of which one appears to be monocytogenic and expressed S100 protein.