Epidermal cell population kinetics after a single application of some hyperplasia-producing substances

Abstract

The initial and the long term effects of a single topical surface application to the skin of hairless mice (hr/hr) of benzene, cantharidin in benzene, and 21-methylcholanthrene in benzene, have been examined. The growth parameters have been evaluated by means of the Colcemid method, which is briefly discussed. The reactions of the epidermal cell population have been interpreted as biological phenomena and in terms of cybernetics. Both benzene and cantharidin provoke alterations in the dynamics of the epidermal cell population that are well compatible with a simple regenerative reaction and can readily be explained in terms of cybernetics. The initial reaction after application of methylcholanthrene was also in conformity with this concept, while the later alterations cannot well be explained as a regenerative reaction. Some other mechanisms appear to be involved. An inverse relationship between the mitotic rate and the mitotic duration could be discerned in all reactions that could be interpreted as simple regenerative reactions. The alterations in the various growth parameters indicated that the mitotic rate might be regulated by a derivative type of negative feedback control, and the mitotic duration by a proportional type.