Antonia Flaks

Fine structure of murine pulmonary adenocarcinomata induced by treatment with 20-methylcholanthrene in organ culture

Abstract Mouse lung tissue was treated with 20 -methylcholanthrene in vitro and then implanted into host animals to await the appearance of tumours. The fine structure of pulmonary adenocarcinomata induced by this method was studied and found to resemble, in some respects, that of similarly induced adenomata and of mouse lung tumours arising spontaneously or induced in vivo . Ultrastructural differences between the adenocarcinomata and the previously described adenomata included increased irregularity of cell-surface membranes, disaggregation of ribosomes and decreased numbers of specific cytoplasmic lamellar inclusion bodies. These differences, as well as the greater variations in cell structure which were observed, appeared to be related to the acquisition of a malignant character by these tumours.

In vitro effects of chemical carcinogens

Abstract The present work has been devised to ascertain the possibility of using an in vitro technique for the classification of chemical agents into proximate and non-proximate carcinogens. Pulmonary explants, derived from one-month old inbred Balb/c females, were maintained in vitro for two days with or without a carcinogen in the medium. They were subsequently implanted subcutaneously into adult mice of the same strain. The implants were examined at three-monthly intervals for one year. The carcinogens examined included 2 -AAF, urethane and INH, while 20 -MeCh medium as well as normal medium provided controls. 20 -MeCh alone proved to be active in a direct manner, judging by the presence of adenomata and adenocarcinomata. On the other hand, the test carcinogens, which require activation in vivo , did not induce neoplastic lesions. The culture method may therefore prove to be useful in investigations of the mechanisms of action of chemical carcinogens.

Pulmonary tumour induction in vitro: genetic influence.

Abstract Pulmonary tissues, taken from C 57 B 1 mice, were incubated in vitro for one day in 20 -methylcholanthrene medium and subsequently implanted into animals of the same strain. Histopathological examination of the implants at periods varying between 3 and 12 months showed the presence of intense lymphocytic hyperplasia but the total absence of adenomata. As C 57 B 1 mice are known to be genetically resistant to the in vivo formation of pulmonary neoplasms and as no neoplasms were induced by the in vitro method, it was considered that tissue-specific genetic factors exercised a dominant role in the activity of the carcinogen.