前立腺のDNA代謝 第2編; 実験的前立腺腫瘍のDNA代謝

Abstract

Injection of 20-MC was done in the anterior lob e of the prostatic gland using male rats of Wistar strain and its carcinogenetic process was observed with HE stain and autoradiography. 1. Following injection of 20-MC in the anterior lobe of the prostatic gland of rats, histological changes progressing in the order of glandular epithel, squamous metaplasia and cancer were confirmed. 2. In autoradio g raphy, both of Tritium Index and mean grain counts were decreased in 3 and 4 days after the 20-MC injection. 3. From around 10 days after injection, squamous metaplasia took place with increased Tritium Index but no carcinomatous change occurred within 50 days. Labelling was localized in only basal layer, wich indicates that the one of devided daughter cell stays in the basic layer with maintaining mitotic ability, while the other loses mitotic ability and is pushed upward followed by falling off. The grain counts distributed in a narrow range with the average of 10 to 14 and the mean grain count was less than normal. 4. Around 150 to 200 days after injection, increased Tritium Index with generalized labelling of some cancer nests became evident. This means that each of devided cell holds mitotic ability. The mean grain counts increased and distribution of grain count showed diphasic pattern in narrow ranges. The findings suggested of qualitative and quantitative alterations of DNA although the cause of change was not conclusively decided as direct or secondary effects of 20-MC. 5. This experimental tumor seemed to be possessed of two different abnormal cell dividing modes ; one is shortening of a generation and the other is maintennance of mitotic ability in both of daughter cells. 6. In the interstitial tissu e , labelled cells increased in number until squamous metaplasia occurred, while they decreased markedly after the cancerous changes developed.