Similitudes and differences in the reactivity of the liver cell chromatin to thioacetamide and hydrocortisone. Electron microscopic and cytochemical quantitative data concerning the chromatin condensation-dispersion cycle.

The administration of thioacetamide (TAA) and/or hydrocortisone to rats brought about dispersion of the heterochromatin in the liver cell, and concomitant stimulation of RNA synthesis in the chromatin. In contrast to other experimental situations in which dispersion of the chromatin persisted for at least 6 hours, after TAA injection dispersion was followed by rapid excess condensation. A hypothesis is suggested concerning the process of induction of malignant proliferation by TAA.