Comparative Light and Electron Microscopical Studies of Decaying Thymic Lymphoid Cells

Abstract

Normal thymic lymphoid cell suspensions were studied in the electron microscope. The suspensions contained cells (6–23 per cent) in various degrees of lytic degeneration with swelling and disintegration of both nucleus and cytoplasm. Only a minority of the degenerating cells showed pyknotic changes and these cells had always a well preserved cytoplasm. The percentage of degenerating cells was compared with the percentage of cells stained in the nigrosin‐dye exclusion test. A close relationship between these two values was found, suggesting that supravital staining primarily affects cells in lytic cell degeneration. It appears that vital stains only affect already degenerating cells with a subsequent increase of a preexisting intracellular edema. This suggestion was corroborated by the finding that addition of nigrosin dye to thymic cell suspensions does not depress aerobic metabolism.